Strikeforce (2006–2010)

Stewart made his professional mixed martial arts debut in 2006, signing with now-defunct promotion Strikeforce in May 2006. He made his debut facing Bill Duvall at Strikeforce: Revenge on June 9, 2006. He won the fight via armbar submission, 1:15 into the first round.^[3]

In his second fight with the promotion, Stewart faced Jeremiah Metcalf at Strikeforce: Tank vs. Buentello on October 7, 2006. He won the fight via rear-naked choke.^[4] He then faced UFC veteran Jason Von Flue at Strikeforce: Shamrock vs. Baroni on June 22, 2007. He won the fight via third round TKO.^[5]

Stewart faced Sam Liera at Strikeforce: Playboy Mansion on September 29, 2007.^[6] He won the fight via first round TKO.^[7] In his fifth fight with the promotion, Stewart faced Bryson Kamaka at Strikeforce: Four Men Enter, One Man Survives on November 16, 2007.^[8] He won the fight via knockout, just 19 seconds into the first round.^[9]

In his next fight, he faced Tiki Ghosn at Strikeforce: Shamrock vs. Le on March 29, 2008.^[10] Despite being a considerable betting favorite coming into the bout, Stewart lost the fight via unanimous decision, the first loss of his professional MMA career.

Stewart faced Jesse Juarez at Strikeforce: At The Mansion II on September 20, 2008.^[11] He won the fight via first round armbar. Joe Riggs at Strikeforce: Destruction on November 21, 2008.^[12] He lost the fight via second round TKO.

After a one-year hiatus from MMA, Stewart returned to face André Galvão at Strikeforce Challengers: Johnson vs. Mahe on March 26, 2010.^[13] He lost the fight via split decision, and subsequently retired from mixed martial arts shortly after.