Firmino began his career at the tenth World Vale Tudo Championship in Recife, Brazil when he was 18 years old.
He made his debut with the organization at its first event, Dream 1, in March 2008 where he submitted Kazuyuki Miyata with a rear-naked choke seven minutes into the first round.
Firmino also returned to fight in his native Brazil for the first time in almost seven years when he faced Francisco Trinaldo at Bitetti Combat MMA 6, where he was submitted with a kneebar.
[4] Firmino competed at Superior Cage Combat 3, where he lost against UFC and Pride veteran, Canadian John Alessio via decision.
[5] Firmino defeated The Ultimate Fighter: Live alumni Johnavan Vistante by submission due to an arm-triangle choke in the first round at CFA 07: Never Give Up in Coral Gables, Florida on June 30, 2012.
Firmino defeated two-time Bellator Tournament finalist, and 2009 Submission of the year winner Toby Imada by unanimous decision at CFA 08 in Hollywood, Florida on October 6, 2012.
[9] After almost two years away from the promotion, Firmino returned in January 2016 to face Strikeforce and UFC veteran Caros Fodor at WSOF 27.