Armstrong made his debut with World Championship Wrestling (WCW) on May 27, 1990, on a house show in Los Angeles, California when he defeated Rick Fargo. Scott started as a preliminary wrestler, teaming with, and later facing, Barry Horowitz.
Scott Armstrong made his return to WCW on January 18, 1994 at a television taping for Main Event where he wrestled Tony Zane. On March 6, he wrestled WCW World Television Champion Lord Steven Regal on Main Event. In August, on WCW WorldWide, Armstrong was defeated by Diamond Dallas Page. On the September 10 episode of WorldWide, he faced Ron Simmons in one of the last WCW matches for the latter. On the December 17 edition of WCW Saturday Night, Armstrong wrestled Jean-Paul Levesque.
Scott began to form teams with his brother Steve Armstrong. At Starrcade on December 27, 1994, Scott teamed with his brother Brad Armstrong and wrestled a dark match against Arn Anderson and Bunkhouse Buck. On the January 7, 1995 episode of WCW Saturday Night, Scott and Brad again teamed against Harlem Heat. A week later on WCW Pro, they would earn their first WCW victory when they defeated Bob Starr and Ricky Santana. On January 25 in a dark match at Clash of the Champions XXX, Brad and Scott defeated Dick Slater and Bunkhouse Buck.
The team with Brad, however, dissolved and Scott Armstrong began teaming with his brother Steve instead. At the July 10 taping of WCW Pro, the WCW World Tag Team Champions Bunkhouse Buck and Dick Slater defeated the duo in their debut match. A month later, on the August 5th, 1995 edition, they fell to Arn Anderson and Ric Flair. On August 22, they faced Men at Work, but were again unsuccessful.
On June 20, 1995, Scott wrestled Ric Flair at a WCW Pro taping in Gainesville, Georgia. On September 16, Disco Inferno would make his successful debut on WCW Saturday Night by pinning Armstrong. He made his first ever WCW pay-per-view appearance at World War 3 on November 26, 1995 when he competed in the three ring battle royal. After being eliminated, he was placed on a stretcher and put in a neck brace.
While wrestling singles matches with Konnan in the first half of 1996, Scott and Steve began competing under their real surnames as the James Brothers from time to time (although they did not change their looks at all). On the February 17 edition of WCW Saturday Night, they again fell to Men At Work. In June 1996, they were defeated by Public Enemy, and on the July 1 edition, they were defeated again by Arn Anderson and Ric Flair. On the July 28, 1996 edition of WCW WorldWide, they fell to Lord Steven Regal and Squire Dave Taylor. On the August 22, 1996 taping of WCW Pro, The James Brothers would finally gain their first WCW victory when they defeated Bill Payne and Rick Thames. They would go on to face The Amazing French Canadians and The Faces of Fear during the remainder of 1996.
The James Brothers would continue teaming in 1997, and faced The Amazing French Canadians and The Steiner Brothers. On the April 13, 1997 edition of WCW WorldWide, they defeated The Southern Posse. After this, they moved on to a brief series of matches with Harlem Heat, and in May 1997 defeated the new duo of Jim Powers and Bobby Walker, the latter put together by Teddy Long. After this, they were winless for the rest of 1997 in matches with Mortis and Wrath, as well as The Public Enemy. Their pairing continued into 1998, but again they saw little success. They were winless against High Voltage in multiple encounters. On the September 13 pay-per-view Fall Brawl, they were involved in an angle when WCW WorldWide announcer Mike Tenay attempted to interview them, only to be interrupted by Ernest Miller, who then attacked both brothers. Thirteen days later, they would defeat The Power Company on WCW Saturday Night. On November 30, 1998, the duo enjoyed the biggest victory of their WCW tenure when they upset Raven and Kanyon on WCW Monday Nitro.
Success continued for The James Brothers in 1999. On January 6, 1999, they upset Alex Wright and Disco Inferno in Mobile, Alabama. On the January 9, 1999 edition of WCW Saturday Night, they defeated Nick Dinsmore and Mike Sullivan. The winning streak came to a stop in April on WCW Saturday Night, when they were defeated by Disorderly Conduct. On April 27, 1999, at a television taping in Bismarck, North Dakota, they faced the nWo for the first time, and defeated Vincent and Stevie Ray. On April 29, 1999, on WCW Monday Nitro, the team faced Raven in a handicap match and were victorious. Scott's teaming with Steve finally came to an end on March 1, 2000, when The James Brothers faced WCW World Tag Team Champions Big Vito and Johnny The Bull at a WCW Saturday Night taping. Shortly thereafter, Steve Armstrong left the promotion, while Scott became a referee.
Armstrong appeared on the July 28, 2006 episode of World Wrestling Entertainment's SmackDown, refereeing the WWE United States Championship match between Finlay and William Regal. In August 2006, Armstrong was hired as a full-time WWE referee, in WWE's ECW brand.
He became senior referee in February 2007 after Mickie Henson was moved to SmackDown.
He was also the only WWE referee for the ECW brand at WrestleMania XXIV. At WWE's SummerSlam pay-per-view event on August 17, 2008, Armstrong refereed the Hell in a Cell match between Edge and The Undertaker. He then moved to the SmackDown brand, becoming its senior official. In November 2008, referees were made no longer exclusive to certain brands.
At WrestleMania XXV on April 5, 2009, Armstrong refereed the main event WWE Championship match between Triple H and Randy Orton. On September 13, 2009, at Breaking Point in Montreal, Armstrong was involved in a storyline in which he made a controversial call on the main event match between World Heavyweight Champion CM Punk and The Undertaker. Armstrong called for the bell and declared Punk the winner, even though The Undertaker never actually submitted defeat, thus making a reference to the Montreal Screwjob (which was held in the same venue in 1997). On October 30, 2009, Armstrong faced CM Punk on SmackDown, but lost in a squash match. The next week, Armstrong fast-counted for R-Truth in his match with Punk, costing Punk the match.
On February 26, 2010, Armstrong was released from his WWE contract.
On February 20, 2011, Armstrong reappeared on WWE programming as the referee for the main event during the Elimination Chamber pay-per-view. He officiated The Undertaker versus Triple H match at WrestleMania XXVII as well as the match between John Cena and CM Punk match for the WWE Championship at Money in the Bank. He returned to SmackDown on August 5, 2011, refereeing the match between The Great Khali and Sheamus. On September 18, 2011, at Night of Champions, Armstrong officiated the main event between Triple H and CM Punk. During a run-in, The Miz and R-Truth verbally abused him, to which Armstrong retaliated by punching The Miz in the face before being beaten down by the two. At TLC: Tables, Ladders and Chairs, Armstrong was Daniel Bryan's referee when he cashed-in his Money in the Bank briefcase and counted the pinfall for Bryan's World Heavyweight Championship victory over Big Show.
In early 2012, Armstrong became a producer for the company. Scott Armstrong also officiated the match between CM Punk and Chris Jericho for the WWE Championship at WrestleMania XXVIII.
On August 19, 2012, at SummerSlam, Armstrong officiated the match between Triple H and Brock Lesnar, in which Triple H told him not to stop the match. At Survivor Series, he was accidentally Brogue Kicked by Sheamus when he was used as a human shield for World Heavyweight Champion Big Show, causing Big Show to lose via disqualification.
At Night of Champions 2013, Armstrong officiated the WWE Championship match between Daniel Bryan and Randy Orton, and made a fast 3-count in favor of Bryan to allow him to win the championship. He was kayfabe fired the next night for his actions. This was later revealed as a ploy to keep Bryan away from the title. Armstrong made another appearance at Battleground, being the second referee of the Bryan-Orton match after the first referee was knocked out, before himself being knocked out by Big Show. Armstrong returned at the main event of WrestleMania XXX, where he was recruited by The Authority to screw Bryan out of the championship, but was kicked out of the ring by Bryan. At Survivor Series, he was sent by Triple H to replace the knocked out referee, but was struck down by the debuting Sting. Afterwards, he didn't appear on WWE programming until the January 4, 2016 edition of Raw, where he tried to help Sheamus win the WWE World Heavyweight Championship against Roman Reigns while the guest referee, Vince McMahon, was knocked out.
On April 15, 2020, Armstrong was released by the WWE along with several other producers.