Foster made his Bellator debut on October 21, 2010 at Bellator 33 where he defeated Lester Caslow via unanimous decision. In January 2011, Bellator announced that Foster will be a part of the and will face 4 time NCAA Division IAll American wrestler, Eric Larkin. At Bellator 37, Foster won via guillotine choke in round 1 to move on to the semifinals. At Bellator 41, he then faced Daniel Mason-Straus, who was on an 11 fight win streak before entering the fight. He lost the fight via guillotine choke in round 3. Foster appeared on the Bellator 53 card against Englishmen, Ronnie Mann. The fight was billed as a qualifier fight for the sixth season featherweight tournament. Foster lost the fight in the first round via submission. Foster took an off fight from Bellator when he competed for Cage Fury Fighting Championships on February 4, 2012. Foster fought undefeated prospect Joey Gambino in the main event for the featherweight championship. Foster lost the fight via unanimous decision. Foster was scheduled to fight Bobby Reardanz on the undercard of Bellator 60 replacing Mike Corey after Corey was asked to replace an injured Wagnney Fabiano in the season six featherweight tournament. However, after weigh-in issues forced Genair da Silva out of the featherweight tournament, Foster was asked to take his place in the tournament and fight Alexandre Bezerra in the opening round. He lost via submission in the second round. Foster then made a quick turnaround and faced Jay Haas at Bellator 65 on April 13, 2012. He won the fight via guillotine choke. He faced Claudio Ledesma at Bellator 74 on September 28, 2012. He lost the fight via unanimous decision. After a short hiatus from MMA, Foster returned to Bellator and faced Anthony Morrison at Bellator 108 on November 15, 2013. He lost the fight via majority decision. Foster then faced Chris Piriz at Bellator 110 on February 28, 2014. He lost the fight via unanimous decision, dropping him to 3–7 in his last ten fights.
Other promotions
Foster faced Andy Main at CFFC 36: Secor vs. Good on June 21, 2014. He won the fight via split decision. Foster faced Mike Santiago for the vacant ROC Featherweight Championship on January 23, 2015 at Ring of Combat 50. He lost the fight via guillotine choke submission in the first round.