Hart made his televised WWF debut on August 29, 1984, in a tag team match where he teamed with the Dynamite Kid. On September 11, in Poughkeepsie, New York, Hart defeated Aldo Marino in his televised debut singles match, which aired on the September 29 episode of Superstars of Wrestling. In 1985, after acquiring the nickname of "Hit Man", he requested to join Jimmy Hart's heel stable, The Hart Foundation, which included brother-in-law Jim Neidhart. Bret began to increasingly team with Neidhart, in order to build the promotion's tag team division. Bret's agile, technical style – which earned him the moniker "The Excellence of Execution" (coined by Gorilla Monsoon) – created a contrast with his partner Neidhart's strength and brawling skills. During this time, Hart began wearing his signature sunglasses.
In 1986, Hart began his first singles program with Ricky Steamboat, and in a singles match originally planned for WrestleMania 2, he lost to Steamboat at the Boston Garden on March 8, 1986. At WrestleMania 2, Hart instead participated in a 20-man battle royal which was eventually won by André the Giant. He lost to Steamboat again on the July 28, 1986 episode of Prime Time Wrestling. Hart headlined his first televised WWF card when he beat Ray Rougeau, of The Fabulous Rougeaus, in the main event of the November 3, 1986 episode of Prime Time Wrestling.
The Hart Foundation won their first of two WWF Tag Team Championships on the February 7, 1987 episode of Superstars of Wrestling when they defeated The British Bulldogs. They then teamed with Danny Davis to face The British Bulldogs and Tito Santana at WrestleMania III. They won the match when Davis pinned Davey Boy Smith after hitting him with Jimmy Hart's megaphone.
The Hart Foundation adopted the nickname, "The Pink and Black Attack", which Hart continued to use after the tag team's disbandment. This was in reference to the team's ring attire, as well as Hart's signature mirrored sunglasses, which he would routinely give away to a young audience member before matches, following his face turn in 1988. As Hart's WWF career progressed, he increasingly described himself as "The best there is, the best there was, and the best there ever will be".
The Hart Foundation lost the WWF Tag Team Championship titles to Strike Force on the October 27 episode of Superstars of Wrestling. Hart subsequently competed in his most high-profile singles contest to date on the November 28, 1987 episode of Saturday Night's Main Event, when he faced "Macho Man" Randy Savage in a losing effort. He began 1988 with a decisive victory over Paul Roma of The Young Stallions (who had scored an upset victory over The Hart Foundation the previous year) on the January 11 episode of Prime Time Wrestling, and, at the Royal Rumble in January 1988, was the first man to enter the Royal Rumble match. He lasted 25 minutes and 42 seconds before being eliminated by Don Muraco. In his first singles championship opportunity, he challenged The Honky Tonk Man for the WWF Intercontinental Championship in the main event of the July 18 episode of Prime Time Wrestling, with the match ending in a double countout.
At the Royal Rumble in January 1989, The Hart Foundation teamed with Jim Duggan to defeat The Fabulous Rougeau Brothers and Dino Bravo. They also defeated Greg Valentine and The Honky Tonk Man, who were also managed by Jimmy Hart, at WrestleMania V. At an event in Milan on April 8, 1989, André the Giant requested to work a singles match with Hart, who lost the match.
At SummerSlam in August 1989, The Hart Foundation lost a non-title match against then WWF Tag Team Champions The Brain Busters. In the first televised contest of a rivalry that would span Hart's WWF and WCW careers, he lost to Mr. Perfect on the November 6, 1989 episode of Prime Time Wrestling, when Perfect pulled Hart's tights during a roll-up. In their first ever singles meeting, Shawn Michaels and Hart wrestled to a double countout on the February 11, 1990 episode of Wrestling Challenge.
After participating at the Royal Rumble in January 1990, The Hart Foundation defeated The Bolsheviks in 19 seconds at WrestleMania VI and began feuding with Demolition, who had just won the WWF Tag Team Championship against The Colossal Connection at WrestleMania VI. At SummerSlam in 1990, The Hart Foundation began their second, and final, WWF Tag Team Championship reign by defeating Demolition members Crush and Smash in a two out of three falls match with some help from the Legion of Doom. On October 30, the Hart Foundation lost the title to The Rockers (Marty Jannetty and Shawn Michaels), but a few days later, WWF President Jack Tunney reversed the decision and the win was never acknowledged on television. The Hart Foundation's reign lasted until WrestleMania VII, where they lost to The Nasty Boys, after which the team split.
Hart won his first WWF Intercontinental Championship by defeating Mr. Perfect with the Sharpshooter at SummerSlam in 1991, and subsequently won the 1991 King of the Ring tournament on September 7, 1991 at the Providence Civic Center in Providence, Rhode Island. Hart's first pay-per-view title defense occurred at This Tuesday in Texas, where he beat the undefeated Skinner.
In January 1992, Hart was placed in a feud with The Mountie. This feud came about when the Mountie's manager, Jimmy Hart, threw water on Hart, and The Mountie proceeded to shock Hart with a cattle prod. On January 17, 1992, Hart dropped the Intercontinental Championship to The Mountie. Following the loss, Roddy Piper defeated Mountie with a sleeper hold two days later at the 1992 Royal Rumble, and Bret later pinned Piper for his second Intercontinental Championship at WrestleMania VIII later that year. At a Wrestling Challenge taping on July 21, 1992, Hart defeated Shawn Michaels, with the Intercontinental Championship belt suspended above the ring, in the WWF's first ever ladder match. Hart dropped the Intercontinental Championship to his brother-in-law, Davey Boy Smith, in Hart's first WWF pay-per-view main event at SummerSlam in August 1992, held before over 80,000 fans at Wembley Stadium.
Hart won the WWF World Heavyweight Championship from Ric Flair at a Superstars taping at Saskatchewan Place in Saskatoon, Saskatchewan on October 12 of that year, in a match not originally broadcast on WWF television – the match was instead made available on a series of Coliseum/WWE Home Video releases. Hart dislocated one of the fingers on his left hand during the match and popped it back in himself so it would not affect the rest of the match. He made his first successful title defense against Papa Shango on Saturday Night's Main Event. He would headline his first pay-per-view as champion with a successful title defense against Shawn Michaels at the 1992 Survivor Series, and defeated Razor Ramon at the 1993 Royal Rumble. He would also defend the title against contenders such as Papa Shango and former champion Ric Flair before losing the title to Yokozuna in his first WrestleMania main event at WrestleMania IX, after interference from Mr. Fuji. Fuji then challenged Hulk Hogan, who had come out to help Hart, to compete for the title; Hogan then won his fifth WWF World Heavyweight Title from Yokozuna. In June, Hart won the first pay-per-view King of the Ring tournament, defeating Razor Ramon, Mr. Perfect, and Bam Bam Bigelow, thus becoming the only two-time King of the Ring. According to Hart, he was scheduled to regain the WWF World Heavyweight Championship from Hulk Hogan at SummerSlam, but Hogan dropped the title to Yokozuna instead at King of the Ring. Hart instead entered a feud with Jerry "The King" Lawler, who interrupted Hart's coronation, claimed he was the only king, attacked Hart and began a barrage against Hart and his family. The two met at SummerSlam in 1993, to determine the "Undisputed King of the World Wrestling Federation". Hart originally won the match by submission, via the Sharpshooter, but as he would not let go of the hold, the decision was reversed to a Lawler victory by disqualification.
After months of dealing with Lawler, Hart received a WrestleMania IX rematch with WWF World Heavyweight Champion Yokozuna on the November 20 episode of WWF Superstars. When Bret appeared to have the match won, with Yokozuna locked in the sharpshooter, Bret's brother Owen Hart came to ringside to congratulate his brother. The referee began questioning Owen's motives, which allowed Fuji to assault Bret. Owen then involved himself in the match, resulting in a victory for Yokozuna via disqualification. On the non-televised but now-canon November 22 episode of Monday Night Raw, Hart again challenged Yokozuna for the WWF World Heavyweight Championship, and again failed to regain the championship due to similar involvement from Owen. The brothers' disagreements set the wheels in motion for a family feud that would span the entirety of 1994. At Survivor Series, the Harts (Bret, Owen, Bruce, and Keith) took on Shawn Michaels (a substitution for Lawler, who was facing legal troubles) and his knights. The Harts won the match, with all of the brothers surviving except for Owen, the only Hart family member eliminated when he was rolled up by Michaels after inadvertently knocking Bret off the apron. Bitter about his elimination, Owen blamed Bret for this and in the weeks ahead, blamed Bret for holding him back. Owen demanded a one-on-one match with Bret, which Bret refused to accept. In the storyline, Bret, along with his parents, worked over the Christmas holidays to reunite the family and to settle their rivalry. Bret was voted "WWF Superstar of the Year" 1993 by fans.
At the Royal Rumble in January, Bret and Owen took on The Quebecers (Jacques and Pierre) for the WWF Tag Team Championship. Referee Tim White stopped the match after he considered Bret unable to continue after he sustained a kayfabe knee injury during the match. After the match, Owen berated his brother for costing him a title opportunity and attacked the injured knee, setting the feud between the two. Later on, Hart managed to participate and win the 1994 Royal Rumble match amid controversy. Hart and Lex Luger were the final two participants and the two were eliminated over the top rope at the same time. Therefore, both men were named co-winners of the 1994 Royal Rumble match and received title shots at WrestleMania X. Luger won the chance to face Yokozuna first, with Hart having to wrestle his brother Owen, before receiving his title shot. Hart lost his match against Owen, but went on to defeat Yokozuna for his second WWF World Heavyweight Championship.
Hart continued to feud with his brother Owen while he also started feuding with Diesel. Hart's friend and former tag team partner Jim Neidhart returned to the WWF and reunited with Hart. At King of the Ring, Hart defended the WWF World Heavyweight Championship against Diesel. When Hart was winning the match, Shawn Michaels interfered on Diesel's behalf; Diesel appeared close to victory after he delivered a Jackknife Powerbomb yet before he could pin Hart, Neidhart interfered, therefore Diesel won by disqualification, but Hart retained his title. Neidhart left when Diesel and Michaels attacked Hart following the match. Neidhart's motivation was made clear when he helped Owen win the tournament that night, so that he could receive a title shot against his brother. At SummerSlam, Hart successfully retained the WWF World Heavyweight Championship against Owen in a steel cage match.
Hart eventually lost his WWF World Heavyweight Championship at Survivor Series in a submission match against Bob Backlund where the manager of either competitor (Davey Boy Smith for Hart, Owen for Backlund) would have to "throw in the towel" for the wrestler they were representing. When Hart was in Backlund's crossface chickenwing and Davey Boy was kayfabe knocked out, Owen persuaded his mother Helen to throw in the towel for Hart, giving Backlund the championship victory. Bret's feud with Backlund would continue into the following year.
Three days after Hart's title loss, Diesel defeated Backland in eight seconds with a jackknife powerbomb to become the new WWF World Heavyweight Champion. Hart challenged for Diesel's WWF World Heavyweight Championship at the 1995 Royal Rumble, in a match that was continually marred by outside interference and ruled a draw. Both men embraced in a display of sportsmanship after the match. In a rematch from Survivor Series, Hart defeated Bob Backlund in an "I Quit" match at WrestleMania XI. Hart would be the focal point of the first event in the In Your House pay-per-view series, competing in two matches at In Your House 1. He defeated Hakushi in the very first match of the in Your House series. Hart's acclaimed feud with Jerry Lawler was reignited at the event when Lawler defeated Hart due to Hakushi's (now Lawler's protégé) interference. Hart beat Lawler in a "Kiss My Foot" match at King of the Ring, and defeated Lawler's kayfabe dentist, Isaac Yankem, by disqualification at SummerSlam 1995. Their King of the Ring match ended with Hart shoving his foot into Lawler's mouth, then forcing Lawler to kiss his own foot. Although Hart was victorious in their in-ring feud, Lawler remained strongly opposed to Hart as a commentator, and would routinely encourage Hart's opponents during matches. After disposing of Lawler, Hart engaged in a three-month feud with Jean-Pierre Lafitte, who would stealing the mirrored sunglasses from fans at ringside and his trademark leather jacket. At In Your House 3, Hart defeated Lafitte, to end the feud. Hart shifted his focus back to the WWF World Heavyweight Championship, defeating Diesel in a no disqualification match at Survivor Series to commence his third reign.
In a rematch from their SummerSlam 1992 encounter, Hart successfully defended his title against the now heel Davey Boy Smith at In Your House 5: Seasons Beatings. He lost to The Undertaker by disqualification at the 1996 Royal Rumble when Diesel interfered, ultimately retaining the WWF World Heavyweight Championship, and defeated The Undertaker by disqualification in a rematch on the February 5 episode of Raw, again due to Diesel's interference. Hart retained his title once again against Diesel in a steel cage match at In Your House 6, and defeated Hunter Hearst Helmsley, who was undefeated on Raw, on the March 4 episode of the show. WWF Commissioner Rowdy Roddy Piper ruled that Hart would face Shawn Michaels, who had earned a WWF World Heavyweight Championship match at WrestleMania XII by winning the Royal Rumble, in a 60-minute Iron Man match at the event. The wrestler with the most decisions during the 60 minutes would win the match and the WWF World Heavyweight Championship.
At WrestleMania, with less than a minute left on the clock and the score still 0–0, Michaels jumped from the middle rope; his legs were caught by Hart, and Hart locked in his Sharpshooter. However, Michaels did not submit in the last 30 seconds so the match ended in a tie. WWF President Gorilla Monsoon ruled that the match would continue in sudden death overtime. Michaels hit a superkick to win the championship. After WrestleMania, Hart went on a European tour over the next two weeks, coming out victorious against Stone Cold Steve Austin and Hunter Hearst Helmsley. The tour ended on April 22, and after this he took his hiatus from television. His final televised appearance was an interview taped while on the European tour.
Over the summer, Stone Cold Steve Austin, who was fresh from winning the 1996 King of the Ring, continually taunted Hart and challenged him to come back and have a match. After an eight-month hiatus from television, Hart returned and defeated Austin at Survivor Series in a match for the number one contender spot to the WWF World Heavyweight Championship. Hart challenged champion Sycho Sid at the following month's In Your House 12: It's Time; Shawn Michaels, who was serving as a guest commentator at ringside, accidentally cost Hart the victory when he attempted to become involved in the match after being assaulted by Sid. The building tension between Hart and Michaels climaxed after the match, when Hart assaulted Michaels. Hart's feud with Austin escalated at the Royal Rumble, when Hart tossed Austin out of the ring, only for Austin (unbeknownst to the referees) to climb back into the ring and win the Rumble, while the referees were distracted by Mankind. Hart quit the WWF the next night on Raw in protest. In order to deal with this controversy, a Fatal Four-Way between Austin and the participants he eliminated after re-entering the ring (Vader, The Undertaker, and Hart) was set up for In Your House 13: Final Four, with the winner becoming the number one contender. After then-champion Shawn Michaels relinquished the belt, though, the match officially became for the WWF World Heavyweight Championship. Hart defeated Austin, Vader, and The Undertaker in the Fatal Four-Way. However, Austin made sure Hart's fourth reign was short-lived, costing him a title match against Sid the next night on Raw. Hart challenged for Sid's WWF World Heavyweight Championship in a steel cage match shortly before WrestleMania 13, which saw Austin actually attempt to help Hart win, in order to make their scheduled match at WrestleMania 13 a title match. Concurrently, The Undertaker, who had a scheduled title match with Sid at WrestleMania, attempted to help Sid win. Sid ultimately retained, leading to a pure grudge match for Hart and Austin. Following his loss to Sid, Hart shoved "announcer" Vince McMahon to the ground when he attempted to conduct a post-match interview, and engaged in a worked shoot, expletive-laden rant against McMahon and WWF management. This incident has been cited as one which helped lay the foundations of the WWF's Attitude Era, as well as the starting point of McMahon's on-air character, the tyrannical WWF owner "Mr. McMahon".
At WrestleMania 13, Hart and Austin had their rematch in a submission match. In the end, Hart locked the Sharpshooter on a bloody Austin, who refused to give up. In fact, Austin never quit, but passed out from the blood loss and pain. Ken Shamrock, the special guest referee, awarded Hart the match, after which he continued to assault Austin, thus turning heel for the first time since 1988. Later that night, Hart confronted Sycho Sid and The Undertaker prior to their match for the WWF World Heavyweight Championship; Hart insulted Undertaker and told Shawn Michaels (who was a guest commentator for the match) not to interfere. Undertaker won the match, which ended with Hart hotshotting Sid on the ropes, therefore costing him the title.
Hart challenged Rocky Maivia for the Intercontinental Championship in the main event of the March 31 episode of Raw. Rocky Maivia won by disqualification when Hart refused to release a figure-four leglock applied around the ringpost. He faced Austin again in the main event of In Your House 14: Revenge of the 'Taker, to determine who would challenge the WWF World Heavyweight Champion in a title match at the following month's In Your House 15: A Cold Day in Hell. Austin had Hart locked in his own finishing move, the Sharpshooter, in the middle of the ring when The British Bulldog interfered on Hart's behalf, resulting in disqualification and giving Austin the victory and title match. They met once again in a street fight on the April 21 episode of Raw Is War, in which Austin injured Hart's ankle with a steel chair. The match was ruled a no contest and Austin afterward continued to beat Hart while on a stretcher in the back of an ambulance.
In the ensuing weeks, Hart denounced American fans, because of their negative reaction to him in the recent weeks in contrast to his continued popularity through the rest of the world, and reunited with brother Owen and brothers-in-law Davey Boy Smith and Jim Neidhart. The family members formed a new Hart Foundation with Brian Pillman; this incarnation was an anti-American stable which was popular within Canada and Europe. As the leader of this stable, Hart routinely carried a Canadian flag to the ring and engaged in promos where he declared the superiority of his home nation; he became so despised by U.S. audiences that they would often throw debris during his ring entrances, interviews, and matches. At In Your House 16: Canadian Stampede, in Hart's home town of Calgary, the Hart Foundation defeated the team of Stone Cold Steve Austin, Ken Shamrock, Goldust, and The Legion of Doom, representing the United States, in a ten-man tag team match main event. The Canada vs. U.S. rivalry escalated on the July 21 episode of Raw Is War in Halifax, Nova Scotia, where Bret, Owen, and Davey Boy Smith, representing Canada and the Hart Foundation, defeated the team of Dude Love, Austin, and The Undertaker, representing the U.S., in a Flag match. Hart vowed that if he could not defeat The Undertaker for the WWF World Heavyweight Championship at SummerSlam, he would never wrestle in the United States again. The Undertaker agreed to the match, and Hart won his fifth and last WWF World Heavyweight Championship after spitting in guest referee Shawn Michaels' face; Michaels swung a steel chair in retaliation, which accidentally struck the Undertaker. Michaels, who, as part of another pre-match stipulation, would be banned from wrestling in the United States if he did not remain impartial as referee, had no option but to count the pinfall, giving his rival Hart the victory.
After SummerSlam, Michaels was pushed as the top heel in the company and negative fan reactions towards Hart in the United States softened somewhat, as he declared, "I'm not so much anti-American as I am just very, very pro-Canadian". Hart successfully defended his title against The Patriot, with whom Hart had become involved in a feud as part of the Canada vs. U.S. storyline, at Ground Zero: In Your House, avenging a loss to him on the July 28 Raw. The Canada vs. U.S. feud would conclude at Badd Blood: In Your House, where Hart and Davey Boy Smith, representing Canada and The Hart Foundation, defeated The Patriot and Vader, representing the U.S., in a Flag match. Erstwhile, in a rematch from SummerSlam, The Undertaker challenged Hart for the WWF World Heavyweight Championship at One Night Only; after reversing a Tombstone Piledriver attempt from Hart, The Undertaker dumped Hart on the apron when he would not let go of the ropes. As a result, Hart's neck was caught in the ropes, and The Undertaker was disqualified.
During the Hart Foundation's feud with the Shawn Michaels-led D-Generation X (DX), DX framed the Hart Foundation in vandalizing the locker room of the African American stable, Nation of Domination with racist motifs. Hart successfully defended his title against Nation of Domination leader, Faarooq, on the October 20 episode of Raw. In his penultimate title defense, Hart wrestled Ken Shamrock to a no-contest on the October 27 episode of Raw Is War; while the referee was knocked out, Shamrock put Hart in an ankle lock; members of the Hart Foundation then attacked Shamrock until Shawn Michaels made the save for Shamrock and attacked Hart.
Around this time, Hart's on-air rivalry with Vince McMahon also escalated. A heated ringside altercation between the two led many fans to dislike McMahon, who at the time was being exposed as owner of the WWF more and more frequently on-air. At Survivor Series, Hart faced Michaels in what would become known as the "Montreal Screwjob". Even though Hart did not submit to the Sharpshooter, referee Earl Hebner called for the bell as if he had, on McMahon's orders. This resulted in Hart "losing" the title to Michaels. The night ended with an irate Hart spitting in McMahon's face, destroying television equipment, and punching McMahon backstage in front of Gerald Brisco, Pat Patterson, and McMahon's son Shane. Hart left the WWF following the incident, and signed with World Championship Wrestling (WCW).
A day after the WWF's Survivor Series pay-per-view, Eric Bischoff, while with the New World Order (nWo), announced that Hart was going to be coming to WCW and joining the nWo. Hart made his debut on Nitro on December 15, 1997. He was also heavily involved in that month's Starrcade pay-per-view. Due to a 60-day no-compete clause from the WWF, he served as the special guest referee for the match between Bischoff and Larry Zbyszko; during the Sting versus Hollywood Hogan main event for the WCW World Heavyweight Championship, he stepped in toward the conclusion of the match as impromptu referee, declaring Sting the winner and new champion by submission. In January, his no-compete clause expired, and his first feud in WCW was against Ric Flair, as both wrestlers considered themselves the greatest professional wrestlers of all time. Hart defeated Flair at Souled Out in his first WCW match. After this, Hart elected to defend the honor of WCW against the nWo, defeating members Brian Adams in his debut Nitro match on March 2, and Curt Hennig at Uncensored. In April 1998, Hart interfered in a Nitro main event between Hollywood Hogan and Randy Savage, helping Hogan recapture the WCW World Heavyweight Championship. He became an associate of the nWo, but did not officially join the group.
Hart competed in his second Nitro match on June 22, defeating Chris Benoit with assistance from nWo members: Hart had attempted to recruit his long-time friend into the nWo, but the offer was rejected. At Bash at the Beach, Hart competed in his first championship match in WCW when he faced Booker T for Booker's WCW World Television Championship. He was disqualified after hitting Booker with a steel chair. He headlined his first Nitro card on July 20, defeating Diamond Dallas Page for the vacant United States Heavyweight Championship, with assistance from nWo member, The Giant. On the August 10 episode of Nitro, Hart lost his title to Lex Luger. He regained it from Luger the next night on Thunder. In the main event of Fall Brawl, Hart was defeated in a WarGames match for the No. 1 contender spot to the WCW World Heavyweight Championship.
Hart subsequently asked the fans for forgiveness, turning his back on Hogan and the nWo. A match between Hart and Hogan was booked for the September 28 episode of Nitro. During the match, Hart sustained a knee injury, with the bout ending in a no-contest; Sting came to Hart's aid and initiated a match with Hogan. Hart turned on Sting, delivering a DDT, and this bout was also ruled a no-contest. Sting, a member of the rival nWo Wolfpac, was assaulted after the match; this betrayal began an intense feud between Hart and Sting. On the October 12 episode of Nitro, Sting and The Warrior beat Hart and Hogan by disqualification. Hart's feud with Sting ended at Halloween Havoc with Hart controversially defending the United States Heavyweight Championship and (kayfabe) injuring Sting. On the October 26 episode of Nitro, Hart lost the title to Diamond Dallas Page. The two headlined the following month's World War 3 pay-per-view in a title match which Hart lost. Hart regained the title from Page on the November 30 episode of Nitro in a No Disqualification match with help from The Giant.
On the February 8, 1999 episode of Nitro, Hart lost the United States Heavyweight Championship to Roddy Piper. On the March 29 episode of Nitro held at Toronto's Air Canada Centre, Hart appeared in street clothes and derided WCW World Heavyweight Champion Ric Flair, as well as Hogan, for avoiding a match with him. Finally, he called out "franchise player" Bill Goldberg, claiming he could beat him in five minutes and verbally coercing Goldberg into giving him the spear. Hart was wearing a metal breastplate under his Toronto Maple Leafs jersey, which resulted in Goldberg being knocked out. Hart then counted his own pinfall over Goldberg's unconscious body and announced over the mic: "Hey Bischoff, and the WCW, I quit!" In reality, he had suffered a groin injury at the hands of Dean Malenko in November and needed time off for surgery.
Hart returned to wrestling on the September 13, 1999 episode of Nitro in a tag team match with Hulk Hogan against Sting and Lex Luger. Hart challenged for Sting's WCW World Heavyweight Championship on the October 18 episode of Nitro, but lost the match when he was attacked by Luger. Due to controversy over a series of WCW World Heavyweight Championship matches between Sting, Hogan, and Goldberg at Halloween Havoc, the title was declared vacant. A tournament then took place over several episodes of Nitro. Hart's first round match came against Goldberg the night after Halloween Havoc, with the bout being a tournament match for a berth in the next round, as well as being a match for the United States Heavyweight Championship that Goldberg had won the night before. Thanks to outside interference, Hart defeated Goldberg and won the title for the fourth time. On the November 8 episode of Nitro, Hart lost the title to Scott Hall in a ladder match which also involved Sid Vicious and Goldberg.
Hart won the WCW World Heavyweight Championship tournament by defeating Perry Saturn, Billy Kidman, Sting, and Chris Benoit at Mayhem. On December 7, Hart and Goldberg won the WCW World Tag Team Championship from Creative Control, making Hart a double champion. Hart and Goldberg lost the tag team titles to The Outsiders on the December 13 episode of Nitro. At Starrcade, Hart defended his WCW World Heavyweight Championship against Goldberg. During the match, Hart was struck with a thrust kick to the head, resulting in a severe concussion. Hart later speculated that he may have suffered up to three additional concussions within matches over the course of that day along with the days immediately following Starrcade, having been unaware of the severity of his injuries. For example, Hart placed Goldberg on the post in a figure four leglock which ended with Hart hitting his head on the concrete floor when Goldberg failed to receive the move correctly. The sum total of those injuries left Hart with post-concussion syndrome and ultimately forced his retirement from professional wrestling. Referee Roddy Piper rung the bell when Hart held Goldberg in the Sharpshooter, although Goldberg did not submit. Piper simply walked away, leaving both Goldberg and Hart bewildered.
Out of respect for Goldberg, Hart vacated the WCW World Heavyweight Championship on the December 20 episode of Nitro and suggested that he, without the championship advantage, face Goldberg that night to determine the true champion. During the match, Scott Hall and Kevin Nash came to the ring looking to attack Goldberg with baseball bats. Hart convinced them to stop, then hit Goldberg with one of the bats. The three continued to beat down Goldberg and were eventually joined by Jeff Jarrett. Hart regained the championship, even though it was Roddy Piper who was covering Goldberg (to try and protect him) when the three count was made. The nWo was reformed (now billed as "nWo 2000"). Hart wrestled Terry Funk to a no contest in a non-title, hardcore rules match on the January 6 episode of Thunder. In his final match in WCW, he defended the WCW World Heavyweight Championship against Nash on the January 10 episode of Nitro, which also ended in a no contest. Hart vacated the title in late January 2000 when he was forced to withdraw from the main event of WCW's Souled Out due to his injuries. Hart continued to make appearances on WCW television, generally cutting promos. On the May 3 episode of Thunder, Hart made a run in during an over the top rope battle royal where he hit Hogan with a chair. His final WCW appearance occurred on the September 6, 2000 episode of Thunder, in a promo where he confronted Bill Goldberg on the injury he sustained nine months prior. WCW released Hart on October 20, 2000, due to his ongoing incapacity, and he announced his retirement from professional wrestling soon afterward.
In mid-2005, Hart worked with the renamed World Wrestling Entertainment for the first time since 1997, contributing hours of interview footage and selecting matches for his WWE Home Video release, Bret "Hit Man" Hart: The Best There Is, the Best There Was, the Best There Ever Will Be. He returned to WWE programming as a guest on the November 16 episode of web series, Byte This.
On April 1, 2006, Hart was inducted into the WWE Hall of Fame class of 2006 by Stone Cold Steve Austin. He did not appear alongside his fellow inductees at WrestleMania 22 the following night. On June 11, 2007, Hart made his first appearance on Raw since October 27, 1997 when he appeared in a pre-taped interview voicing his opinions on Vince McMahon as part of "Mr. McMahon Appreciation Night."
Hart re-signed with WWE in late 2009. On December 28, after weeks of speculation surrounding Hart and his presence in World Wrestling Entertainment, Chairman Vince McMahon announced that Hart would be special guest host on the January 4 Raw. Hart thanked the fans for their continued support, jokingly teased announcer Jerry Lawler about their long-running 1990s feud, and confronted Shawn Michaels and McMahon regarding the Montreal Screwjob at Survivor Series in 1997. Hart and Michaels were able to agree on a truce, shaking hands and hugging. It also appeared that he had buried the hatchet with McMahon later in the night, until McMahon subsequently kicked Bret in the crotch.
During different encounters the following month, Hart and McMahon reproduced events similar to those that occurred in the Montreal Screwjob: McMahon spitting in Hart's face (as Hart did to McMahon), and Hart destroying parts of the technical equipment that goes into producing Raw (as he did to the Survivor Series equipment). On the February 15 Raw, Hart made a farewell from WWE, but as he left to go inside his limousine, another vehicle reversed into the door of his limo and injured his left leg. On the March 1 Raw, McMahon challenged Hart to a match at WrestleMania XXVI; Hart accepted. The match was later changed to a No Holds Barred match as Hart revealed (with help from "Stone Cold" Steve Austin, the special guest host that night) the staging of his injury. Hart, along with his family, inducted his father Stu Hart into the WWE Hall of Fame class of 2010, a controversial decision that aggravated Hart and McMahon's rivalry in 2010. At WrestleMania, McMahon attempted to buy Hart's family into turning against him; however, they turned against McMahon instead and helped Hart defeat McMahon.
Hart stood with The Hart Dynasty (David Hart Smith and Tyson Kidd), a stable stemmed from the Hart family, throughout their feud with ShoMiz (Big Show and The Miz); they ultimately won the WWE Tag Team Championship on April 26. When The Miz lost a match that guaranteed a WWE United States Championship match to a Hart family member, he chose Bret; with the help of the Dynasty, Hart defeated The Miz to win his fifth United States Championship on May 17 in Toronto, Ontario, Canada. On the May 24 episode of Raw, Hart was named the new general manager of Raw. His first orders included vacating his United States Championship, which R-Truth won, and setting up qualifying matches for Fatal 4-Way, which the injured Batista took exception to and quit. The next week, Hart declared a Viewer's Choice episode of Raw. He was attacked by NXT rookies after firing Wade Barrett and declining to offer them contracts on the June 14 episode of Raw. A week later, McMahon fired Hart as general manager for failing to control the rookies.
Hart returned five weeks later, where it was announced by John Cena that he, The Great Khali, R-Truth, Edge, Chris Jericho, John Morrison and Hart would face the NXT rookies, now known as The Nexus, at SummerSlam. The following week, Hart teamed with Cena to wrestle SummerSlam teammates Edge and Chris Jericho to a no contest. In the SummerSlam main event, he was disqualified for using a steel chair on Skip Sheffield, however, his team still ultimately won the match. On the August 16, episode of Raw, Hart introduced the new tag team title belts to the champions, The Hart Dynasty. Later on in the night during The Nexus vs. Raw challenge, Hart was scheduled to face Justin Gabriel, but was unable to compete after the Anonymous Raw General Manager, citing his disdain for Hart, removed him from the match and replaced him with Randy Orton. On September 25, WWE hosted a tribute event to Hart in Madison Square Garden, where he and the Hart Dynasty defeated Nexus members Heath Slater, Justin Gabriel and Michael Tarver in a six-man tag team match, when Gabriel submitted to Hart's Sharpshooter. In November 2010, Hart's WWE contract had expired.
At Over the Limit, Hart came to the support of his long-running 1990s rival, Jerry Lawler, forcing Michael Cole to kiss Lawler's foot. The following night on Raw, Hart refereed the main event, which saw John Cena and Rey Mysterio defeat R-Truth and CM Punk with Hart's assistance. On the August 23, 2011 tapings of SmackDown (aired August 26), Hart served as guest general manager. On September 12, Hart teamed with John Cena in a match against Alberto Del Rio and Ricardo Rodriguez, which he won after putting Rodriguez into a sharpshooter. This was Hart's final match.
Hart has made infrequent appearances in minor roles, appearing on the April 25, 2011 episode of Tough Enough. At Raw 1000 and on the May 4, 2012 episode of Raw he served as guest ring announcer; he interviewed John Cena on September 10, 2012, during which CM Punk interrupted and got into a confrontation with Hart. He participated in backstage segments at the 2013 Royal Rumble and WrestleMania 31. On the post-show of Raw on May 27, 2013, Hart was honored by the city of Calgary and the WWE with a "Bret Hart Appreciation Night", a celebration of the work he had done in his career. Also present in the ring for this celebration were Pat Patterson, Chris Jericho, Shawn Michaels and Vince McMahon, who each paid their own tributes to Hart. He has also served as an expert on panels, including the March 25, 2013 episode of Raw and at the NXT Arrival pre-show. Hart was in the corner of his niece Natalya on the March 27, 2014 episode of NXT, at the second NXT TakeOver event, and at the 2016 Payback event. The match ended when the referee, Charles Robinson, called for the bell as Charlotte had Natalya locked in the Sharpshooter. After the match both Natalya and Hart placed Charlotte and her father, Ric Flair, respectively in the Sharpshooter.
On April 6, 2019, Hart became a two-time WWE Hall of Famer when he was inducted as a member of The Hart Foundation alongside Jim Neidhart. During Hart's speech, an audience member charged into the ring and tackled Hart and his niece Natalya to the ground, but they were quickly saved by multiple wrestlers and security, and after several minutes, Hart continued his speech.