Simmons joined World Championship Wrestling (WCW) in 1986, appearing on the first show of the Great American Bash tour when he defeated The Tahitian Prince in Lakeland, Florida on July 1. Simmons wrestled only preliminary level competition that summer, but on August 7, he scored the biggest victory of his career at that time when he defeated Ivan Koloff in St Louis. Five days later on a house show in Los Angeles, Simmons defeated a young Rodney Anoa'i. On September 5, the rookie defeated The Barbarian in Baltimore.
He remained undefeated in singles actions until finally losing to Ivan Koloff at a house show at the Omni in Atlanta on February 14, 1988. Simmons was dominant through the first half of the year against lower level competition on house shows, including Shaska Whatley and The Terminator. Simmons teamed with Steve Williams at the third annual Jim Crockett Sr. Memorial Cup in Greenville, South Carolina on April 22, 1988. They were defeated in the opening round by Mike Rotunda and Kevin Sullivan when Simmons was hit with a foreign object. In December, he finally entered the first sustained losing streak of his career as he dropped multiple house show matches to Mike Rotunda.
Soon after, in March 1989, Simmons began showing signs of a heel turn as he got more aggressive in his matches, including a non-title match against fellow babyface, then-WCW World Heavyweight Champion Ricky "The Dragon" Steamboat and a match on the April 29, 1989 episode of World Championship Wrestling, where he broke the rules during what was supposed to be a face versus face match against Junkyard Dog. Simmons won the match when the referee, Ron's future manager Teddy Long made a fast count (Long was fired (kayfabe) as referee by Jim Herd immediately following this match). He completed his heel turn on the May 27 episode of World Championship Wrestling during a tag team match, where he teamed with Ranger Ross against the Samoan Swat Team as part of a tournament for the vacant WCW World Tag Team Championship, leaving him in the ring alone when Long came out. Simmons later teamed up with Butch Reed to form Doom. In the beginning, the members of Doom were masked and only known as Doom #1 and Doom #2, managed by Woman. In their pay-per-view debut at Halloween Havoc 1989, Doom defeated The Steiner Brothers. In the "Iron Team Tournament" at Starrcade 1989, Doom finished fourth, losing all three of their matches. Doom's misfortune continued as Woman soon dropped the team to manage The Four Horsemen. Then on February 6, 1990, at Clash of the Champions X, Doom hit rock bottom when they were defeated by Rick and Scott Steiner and as a result of the stipulation were forced to unmask.
With new manager Long, they rebounded and defeated The Steiner Brothers for the WCW World Tag Team Championship at Capital Combat in 1990. They held the title for nine months, defeating teams like The Rock 'n' Roll Express and feuding with The Four Horsemen. Among their most memorable encounters during their title reign was a street fight against Horsemen Arn Anderson and Barry Windham at Starrcade 1990 which ended in a no-contest when Windham pinned Simmons while Reed simultaneously pinned Anderson. Doom finally lost the titles to The Freebirds at WrestleWar in February 1991. Subsequently, Doom broke up, with Simmons turning face and feuding with Reed, defeating him in a cage match at the very first SuperBrawl. Simmons defeated midcarders including Oz and The Diamond Studd, then unsuccessfully challenged Lex Luger for the World Heavyweight Championship at Halloween Havoc, losing the best-of-three-falls match one fall to two.
Simmons spent the first half of 1992 feuding with Cactus Jack, whom he defeated via pinfall at SuperBrawl II. On August 2, 1992 at a house show in Baltimore, Maryland, a scheduled title match between Sting and WCW World Heavyweight Champion Big Van Vader was canceled after Jake Roberts (kayfabe) injured Sting. WCW President Bill Watts responded by holding a raffle to determine the number one contender. Simmons won the raffle and defeated Vader with a snap scoop powerslam to win the championship. By defeating Vader, Simmons became the first recognized African American WCW World Heavyweight Champion.
Simmons held the title for five months. He continued to feud with Cactus Jack, with Jack bringing in The Barbarian to challenge Simmons at Halloween Havoc. At Starrcade, Simmons was scheduled to wrestle Rick Rude, but due to Rude being injured he faced "Dr. Death" Steve Williams instead, wrestling to a double countout that was changed to a disqualification win for Simmons when Williams attacked him after the match. His title reign ended two days later on December 30, 1992, when Vader defeated him to regain the title.
Afterwards, Simmons was relegated to mid-card status, eventually becoming a bitter heel who felt like the fans abandoned him after he lost the championship. Simmons unsuccessfully challenged Dustin Rhodes for the United States Heavyweight Championship and Paul Orndorff for the World Television Championship during his last months with WCW. In the spring of 1994, Simmons was working for WCW without being signed to a contract, also Simmons was briefly managed by Sherri Martel during this time. Simmons competed in the European Cup Tournament, winning his first round match against Marcus Bagwell but lost the next round to Sting. He would go on to feud with Sting and Bagwell, mostly competing in tag matches. His final match was a win over Scott Armstrong on the September 10, 1994 edition of WCW Worldwide.
Simmons appeared in Extreme Championship Wrestling (ECW) from late 1994 to early 1995. During that time he unsuccessfully challenged ECW World Heavyweight Champion Shane Douglas at November to Remember and had matches with Mikey Whipwreck and 911.
After ECW, Simmons joined the World Wrestling Federation (WWF) and made his debut on the July 22, 1996, episode of Monday Night Raw. His first gimmick was that of Faarooq Asad, a gladiator who wore a black and blue gladiator outfit with a misshaped helmet and was managed by Sunny. Simmons started his first feud with Ahmed Johnson before shortening his ring name to Faarooq. The feud was started when Faarooq attacked Ahmed during a tag team match pitting Johnson and Shawn Michaels against the Smoking Gunns. As a result of the injuries sustained, Johnson vacated the Intercontinental Title. In the subsequent tournament, Faarooq lost in finals to Marc Mero. Faarooq dropped his gladiator gimmick, parted ways with Sunny and formed the Nation of Domination (NOD). They mostly feuded with Ahmed Johnson. At Royal Rumble 1997, Faarooq defeated Johnson by disqualification. In the Royal Rumble match, Johnson eliminated himself when he saw Faarooq in the aisle and chased after him. Later in the same match Faarooq was eliminated when Johnson returned and attacked him with a 2x4. At WrestleMania 13, Johnson recruited the Legion of Doom in a winning effort against the entire Nation in a Chicago Street Fight.
After losing to WWF World Champion The Undertaker, at the 1997 King of the Ring, Faarooq blamed Crush and Savio Vega for his loss and threw them out of the NOD. Both formed their rival factions, known respectively as The Disciples of Apocalypse and Los Boricuas, and Faarooq recruited more African American members for the Nation, including half-Samoan Rocky Maivia. The three stables feuded with one another throughout 1997. In the Summer of 1997, Faarooq again lost a tournament final for the Intercontinental title, this time to Owen Hart after Stone Cold Steve Austin interfered. Austin, who had forfeited the title due an injury inflicted by Hart, wanted Hart to win so he could again beat him for the title.
In early 1998, Faarooq's leadership of the NOD was increasingly challenged by Maivia, who had shortened his name to The Rock and felt he should be the leader as he was now Intercontinental Champion. In the Royal Rumble match, all five NOD members were in the ring at the same time and frequently brawled with each other, Faarooq even eliminating his fellow members D'Lo Brown and Mark Henry; he was one of the final three along with the Rock and Stone Cold Steve Austin. Faarooq wanted the Rock to help him eliminate Austin but the Rock refused and eliminated Faarooq. The following month at No Way Out, the Nation of Domination lost a 10-man tag to Ken Shamrock, Ahmed Johnson, Chainz, Skull and 8-Ball when The Rock submitted to an ankle lock by Shamrock. After the match, Faarooq and Rock almost came to blows. At WrestleMania XIV, Faarooq and Kama were unsuccessful in the tag team battle royal. Later in the evening, Faarooq was the only NOD member absent from Rock's title defense against Ken Shamrock. When Shamrock put Rock in an ankle lock, Faarooq ran down to the ring but decided against helping him and walked off, with the crowd cheering his decision. The following night on Raw, Rock assumed leadership of the NOD and kicked Faarooq out of the group. Faarooq spent the next several months feuding with his former stablemates.
After being dumped from the Nation, Faarooq feuded with the Rock but failed to win the Intercontinental title. Simmons then teamed briefly with 2 Cold Scorpio. In late 1998, Simmons began teaming with Bradshaw as The Acolytes, a violent tag team sporting occult symbolism on their tights and chests. They were managed by The Jackyl until he left the WWF, at which point they were reintroduced as members of The Ministry of Darkness led by The Undertaker. The Acolytes recruited Phineas I. Godwinn and Mabel to the Ministry by kidnapping and brainwashing them (renaming them Mideon and Viscera, respectively), and feuded with The Undertaker's rivals, such as D-Generation X and The Brood, the latter of which later joined the Ministry as well.
During this time, the Acolytes had two short reigns as WWF Tag Team Champions; they defeated the team of Kane and X-Pac but lost the titles to the Hardy Boyz. At the Fully Loaded pay-per-view in 1999, they won the titles back in a no disqualification handicap match against the Hardyz and Michael Hayes. Their second reign ended when they lost the titles to Kane and X-Pac.
After the Undertaker suffered an injury in late 1999, the Ministry of Darkness disbanded. Faarooq and Bradshaw continued to team with one another, and eventually adopted the gimmick of two brawlers who enjoyed drinking beer and smoking cigars. After Bradshaw began hiring out the services of the Acolytes as mercenaries and bodyguards, the tag team was renamed the "Acolytes Protection Agency" (APA). Around this time, Faarooq adopted his "Damn!" catchphrase. The team won their third tag team titles by defeating the Dudley Boyz in June 2001 but lost the titles the following month to Diamond Dallas Page and Chris Kanyon when Test interfered.
The APA teamed together until 2002, when Faarooq was drafted to the SmackDown brand. Around this time, Ron Simmons began wrestling under his real name once again. Simmons had a brief heel run when he teamed with Reverend D-Von until he left television in December 2002, but in June 2003 he returned to WWE with Bradshaw, and the APA reunited.
In his last WWE storyline, he was fired by temporary SmackDown General Manager Paul Heyman after the APA lost another match for the WWE Tag Team Championship. It was assumed that the APA was fired, but Paul Heyman told Bradshaw he was allowed to stay. Simmons retired from his in-ring career, accusing Bradshaw of not being a faithful friend in storyline.
Starting on October 23, 2006, he began making short cameos on Raw to say his catchphrase "Damn", often in awe of or shock at odd occurrences.
On the November 20, 2006 edition of Raw, Simmons was chosen by Ric Flair to replace the injured Roddy Piper at the Survivor Series to take on the Spirit Squad. He was the first to be eliminated, via countout. On the January 15, 2007 episode of Raw, he was seen in the ring with Chris Masters in the "Master Lock Challenge", which ended prematurely after interference from Super Crazy. Simmons's escaping the Master Lock, was not recognized. On the July 27, 2007 edition of SmackDown, Simmons was named the best man for Theodore Long and Kristal's wedding.
Simmons also feuded with Santino Marella. On the September 10, 2007 episode of Raw, Simmons was attacked by Marella. On the September 24, 2007, edition of Raw, Simmons returned to the ring and defeated Santino Marella by countout after Marella left the ring and walked out. Simmons occasionally competed on WWE Heat, taking on jobbers from the town in which the show is being taped. At the end of each match, Simmons held a microphone, pulling it toward and away from his mouth while the crowd cheered him until he eventually uttered his catchphrase. On the December 3, 2007 episode of Raw, Simmons and Bradshaw were hired by Hornswoggle to help him in a no disqualification handicap match against Jonathan Coachman and Carlito.
On Raw's 800th episode on November 3, 2008, Simmons interrupted wrestlers, who were dancing in the ring, with his catchphrase. During the 2008 Slammy Awards, he gave The Great Khali the award for the DAMN Moment of the Year. Simmons was released from WWE on January 13, 2009, due to budget cuts but repeatedly reappeared on various WWE events to interrupt awkward situations with his catchphrase. Occasions include episodes of WWE Old School Raw (November 15, 2010 and January 6, 2014) and Raw (May 2, 2011 and January 28, 2013), Hell in a Cell 2012 and WrestleManias 30 and 31.
In 2012, Simmons was inducted into the WWE Hall of Fame by Bradshaw. Simmons and Layfield reunited as the Acolytes Protection Agency (APA) on the 1000th episode of Raw, providing their signature protection and back-up for Lita during her match with Heath Slater. After Layfield hit Slater with the Clothesline from Hell, Simmons took to the microphone exclaiming "Damn!"
On the January 19, 2015 episode of Raw, during a "Raw Reunion" segment, Simmons came out to help the nWo (Scott Hall, Kevin Nash, and X-Pac) and The New Age Outlaws (Billy Gunn and Road Dogg) and John "Bradshaw" Layfield against the Ascension (Konnor and Viktor).
Simmons appeared at the Raw 25 Years show on January 22, 2018 and attended the 2018 WWE Hall of Fame ceremony. He also appeared at the Raw Reunion show on July 22, 2019 in a backstage segment involving Mike and Maria Kanellis, Eve Torres, and Jimmy Hart; using Hart's megaphone to exclaim "Damn!".