Born and raised in Spokane, Washington, Sicilia competed in wrestling at Mt. Spokane High School and now works as an assistant coach for the team.
Sicilia began training in MMA in 2007, taking his first amateur fights late in the year before turning professional shortly after. Following his first professional win he took a nearly four-year break from fighting. He then returned in 2011, and went 9-1 fighting for several regional promotions in the Northwestern United States.
In February 2012, it was revealed that Sicilia was selected to be a participant on The Ultimate Fighter: Live. Sicilia defeated Dominick Cruz training partner, Erin Beach, via an eight-second KO to move into the Ultimate Fighter house, and become an official cast member.
Sicilia was selected as the second pick (third overall) by Dominick Cruz to take part on Team Cruz. In the first round of the tournament, Sicilia was selected to fight former Bellator Fighting Championships fighter, Chris Saunders. Sicilia lost the fight via split decision after two rounds. The decision was heavily disputed by many, including UFC president Dana White who claimed, "I think Sicilia got robbed of the opportunity of going to a third round, though. But great fight."
Sicilia made his UFC debut at The Ultimate Fighter 15 Finale on June 1, 2012 in Las Vegas, Nevada against TUF castmate, Cristiano Marcello. He won the fight via KO in the second round. After the win Sicilia expressed interest in returning to the featherweight division.
Sicilia dropped to the featherweight division and faced Rony Jason on October 13, 2012 at UFC 153. Sicilia lost via second-round TKO due to punches.
Sicilia next face Maximo Blanco on April 13, 2013 at The Ultimate Fighter 17 Finale. He lost the fight via unanimous decision.
Sicilia was expected to face Godofredo Pepey on September 4, 2013 at UFC Fight Night 28. However, Pepey pulled out of the bout citing an injury and was replaced by Felipe Arantes. Subsequently, Sicilia also pulled out of the bout for undisclosed reasons and was replaced by Kevin Souza.
The bout with Pepey eventually took place on November 9, 2013 at UFC Fight Night 32. Sicilia won the fight via TKO in the first round.
Sicilia faced Cole Miller on January 15, 2014 at UFC Fight Night 35. He lost the fight via submission in the second round.
Sicilia was expected to face promotional newcomer Doo Ho Choi on May 24, 2014 at UFC 173. However, Choi pulled out of the bout citing an injury. Sicilia instead faced promotional newcomer Aaron Phillips. He won the fight via unanimous decision.
Sicilia faced Katsunori Kikuno at UFC Fight Night 52 on September 20, 2014. He lost the fight via submission in the second round.
Sicilia next fought Akira Corassani on January 24, 2015 at UFC on Fox 14. Sicilia won the fight via KO in the first round.
A rescheduled bout with Doo Ho Choi was expected to take place on July 15, 2015 at UFC Fight Night 71. However, Choi pulled out of the fight in late June for undisclosed reasons and was replaced by Yaotzin Meza. Sicilia won the fight by unanimous decision.
A bout with Choi was scheduled a third time and took place on November 21, 2015 at UFC Fight Night 79. Sicilia lost the bout via TKO in the first round.
Sicilia next faced Gabriel Benítez on September 17, 2016 at UFC Fight Night 94. He lost the fight via submission in the second round.
Sicilia faced promotional newcomer Gavin Tucker on February 19, 2017 at UFC Fight Night 105. He lost the fight via unanimous decision.
In May 2017, Sicilia was released from the company.
On August 17, 2017, it was announced that Sicilia signed with Bellator MMA.
Sicilia was featured in the award-winning mixed martial arts documentary Fight Life, the film is directed by James Z. Feng and released in 2013.