In 1989, Pillman began wrestling for World Championship Wrestling (WCW), where he was known as Flyin' Brian due to his athletic ability and variety of aerial maneuvers. He held the WCW United States Tag Team Championship with The Z-Man between February 1990 and May 1990. Pillman later feuded with Barry Windham, who he harassed while dressed as the masked Yellow Dog after losing a Loser Leaves WCW (Pillman was eventually reinstated). He also held the short-lived WCW Light Heavyweight Championship twice between October 1991 and February 1992, feuding with Brad Armstrong, Jushin "Thunder" Liger, Richard Morton, and Scotty Flamingo.
Pillman turned heel in September 1992, frustrated by Brad Armstrong's knee injury and vacating the WCW Light Heavyweight title, when he was scheduled to wrestle Armstrong for the title at Clash of the Champions XX. In November 1992, he formed a team with Barry Windham, gunning for the WCW World Tag Team Championships held by Ricky Steamboat and Shane Douglas. Windham and Pillman lost to Steamboat and Douglas at Starrcade on December 28. Their team lasted until January 1993, as Windham had his sights on the WCW World Heavyweight Championship.
Pillman continued the tag team title hunt by forming a tag team with "Stunning" Steve Austin known as The Hollywood Blonds. On the March 27, 1993 episode of Power Hour, the duo won the championships from Steamboat and Douglas.
After the feud with Steamboat and Douglas ended, they went on to feud with The Four Horsemen, mainly Ric Flair and Arn Anderson, mocking their ages and parodying Flair's interview show, "A Flair for the Gold", with their own called "A Flair for the Old". They would lose the WCW World Tag Team Titles to Anderson and Paul Roma at Clash of the Champions XXIV (Lord Steven Regal substituted for Pillman, who suffered a leg injury in a tag team match on an episode of WCW Main Event prior to the Clash of Champions). After the Hollywood Blonds separated in October 1993, Pillman became a face, feuding with his old partner Austin. He would also pursue the WCW World Television Championship, held by Lord Steven Regal, with whom he wrestled to a 15-minute time limit draw at Spring Stampede.
Pillman would venture into Extreme Championship Wrestling (ECW) in 1994, as part of a talent exchange between ECW and WCW. His most notable match there was teaming with Shane Douglas to replace an injured Steve Austin, with Sherri Martel as their manager, in a losing effort to Ron Simmons and 2 Cold Scorpio.
Pillman made his return to WCW in January 1995, feuding with wrestlers such as Brad Armstrong, Eddie Guerrero, Alex Wright and Marcus Bagwell by the fall. In September 1995, Pillman formed a team with Arn Anderson and began feuding with Ric Flair. On September 4, 1995, Pillman wrestled the first match on the inaugural episode of Monday Nitro by defeating Jushin "Thunder" Liger in a SuperBrawl II rematch. After costing Flair a match to Arn Anderson at Fall Brawl, Flair recruited the help of Sting to team up against Pillman and Anderson at Halloween Havoc. Pillman and Anderson attacked Flair before the match, forcing Sting to come out alone. When Sting needed a tag the most, Flair came out at the last minute with a bandage on his head, tagged Sting and immediately turned and attacked him removing the fake bandage from his head to show it was all a plan between Pillman, Anderson and Flair from the start. These actions signaled the reuniting of The Four Horsemen. This incarnation was Flair, Anderson, Pillman and Chris Benoit.
At the end of 1995, Pillman developed his "Loose Cannon" gimmick, cultivating a reputation for unpredictable behavior. During this period of time, Pillman changed his once Hollywood Blond and Flyin' Brian clean athletic look for an edgy, out of control image. Even his allies in the Horsemen, especially Anderson, were wary of his behavior and tried in vain to keep him in check. Almost all of the time Pillman could be seen wearing leather vests, sunglasses, jewelry and graphic T-shirts with skulls, monsters and sayings on them. Pillman frequently blurred fact and fiction with his worked shoots.
Pillman outed Kevin Sullivan as booker during the February 1996 SuperBrawl VI pay-per-view in an I Respect You Strap match where the loser announces that they respect the other wrestler, much like an "I Quit" match. Pillman lost to Sullivan, after Pillman grabbed the microphone and said to Sullivan "I respect you, booker man." The next day after SuperBrawl VI, Pillman was released from WCW.
Immediately following his departure from WCW, Pillman returned to ECW and appeared at CyberSlam, on February 17, 1996. During an interview conducted in the ring by Joey Styles, Pillman insulted Eric Bischoff. Although he did not wrestle for ECW, Pillman made several further appearances with the promotion, engaging in a war of words with Shane Douglas, setting up a proposed feud.
Pillman signed a contract with the World Wrestling Federation (WWF) on June 10, 1996. Pillman acted as a commentator while recovering from a broken ankle, transitioning to a wrestling role after attacking a unruly fan during an episode of Shotgun Saturday Night on June 30, 1996 in Detroit.
On the November 4 episode of Raw, Pillman took part in the infamous "Pillman's got a gun" angle with his former teammate Stone Cold Steve Austin. When Pillman initially arrived to the WWF, he aligned himself immediately with his long-time friend and former teammate Austin, serving as his lackey while he recovered. However, Pillman began noticeably favoring Austin's nemesis, Bret Hart, before Austin had enough and brutally attacked him in the ring during an interview on an episode of Superstars on October 27, 1996. Austin and Pillman had been feuding for several weeks, and Austin finally decided to take matters into his own hands and visit Pillman, whom he had already injured, at his home in Walton, Kentucky. WWF interviewer Kevin Kelly sat in Pillman's house with a camera crew and the Pillman family, while Pillman's friends surrounded the house to protect him. Austin was attacked by Pillman's friends as soon as he arrived, but he quickly subdued them. He then proceeded to break into Pillman's home and advance on his nemesis. However, Pillman responded by producing a pistol that he had displayed earlier and pointing it at a hesitant Austin, while Kelly and Pillman's wife Melanie screamed for help. The camera feed was then disrupted, with the scene fading to black. The on-scene director contacted commentator Vince McMahon and reported that he had heard "a couple explosions". The transmission was restored shortly before the end of Raw, and viewers witnessed Pillman's friends dragging Austin from the house while Pillman aimed the gun at Austin.
After WrestleMania 13, Pillman returned and aligned himself with Bret Hart, Owen Hart, The British Bulldog, and Jim Neidhart as part of the anti-American Hart Foundation, turning Pillman heel. He began feuding with his former partner, Steve Austin. In the course of the feud, Austin was given on-screen credit for damaging Pillman's ankle in late October 1996 after placing it in between the seat and backrest of a folded chair and then jumping on the chair. On July 6 at In Your House 16: Canadian Stampede in Bret's hometown Calgary, Pillman and The Hart Foundation defeated the American team of Stone Cold Steve Austin, Goldust, Ken Shamrock and The Legion of Doom in a 10-man tag team match in the main event.
After his feud with Austin, he feuded with Goldust over Marlena until his death. Pillman defeated Goldust at In Your House 17: Ground Zero. This turned out to be his final WWF pay-per-view appearance. During the feud they would for several weeks later appear in segments called "Brian Pillman's XXX-Files", in which Marlena was made to wear sexually provocative clothing. His final WWF televised match on the October 4 episode of Shotgun Saturday Night, defeating The Patriot by disqualification due to interference by Goldust. After the match, Goldust chased him and Marlena out of the arena before the pay-per-view event on the next day.
On October 5, 1997, Pillman was scheduled to wrestle with Dude Love at the WWF pay-per-view In Your House 18: Badd Blood. However, he would not be able to make the show as he tragically passed away that day.