The son of Ricardo and Debbie Erosa, Julian was born in Seattle, Washington but moved to Yakima growing up. Julian has a younger brother, Ricky. Growing up Julian was an avid skateboarder and snowboarder. During his skateboarding years, he frequently got into fights and eventually drifted into mixed martial arts in his late teens.
After going 10–0 as an amateur, Erosa began his professional mixed martial arts career in 2010. He fought primarily in the Pacific Northwest region, mostly in the CageSport promotion. After racking up 7–0 record, he faced Ryan Mulvihill in a rematch for the vacant CageSport Featherweight Championship at CageSport 19 on April 28, 2012. He won the title but was not able to defend it in a match against Drew Brokenshire at CageSport 22 on December 1, 2012. After losing the title, Erosa went 3–1 before receiving a title shot for the vacant CageSport Lightweight Championship. He faced Harrison Bevens at SFL America 2 on December 13, 2014 and claimed the title via knockout. Subsequently, he was pitted against Drew Brokenshire in a rematch for the vacant CageSport Featherweight Championship at SFL America 3 on February 21, 2015. He avenged the previous loss and became simultaneous two-division champion via third-round submission.
Erosa was then picked to be a part of, in which he advanced from the preliminary fights by defeating Jason Soares via unanimous decision. In the elimination round, Erosa faced Mehdi Baghdad. Erosa won the fight via majority decision, advancing into quarter-finals where he took on Abner Lloveras. Erosa advanced to the semi-finals via a split decision victory. In the semi-finals Erosa met the season's would-be runner-up Artem Lobov. He was eliminated from the tournament via first-round knockout loss.
Despite being eliminated from the tournament, Erosa signed a contract with the UFC and made his promotional debut against fellow The Ultimate Fighter alumni Marcin Wrzosek at on December 11, 2015. Erosa won the fight via split decision. He would then face Teruto Ishihara at UFC 196 on March 5, 2016. Erosa lost the fight via second-round knockout and was subsequently released from the promotion.
Return to Cagesport and Other Organizations
After his release from the UFC, went on to fight at a variety of organizations, including Prime Fighting, where he would win the Featherweight title with a TKO win over Austing Springer, as well as losing to Paddy Pimblett in the Cage Warriors Featherweight title fight, in a somewhat controversial unanimous decision. He would then return to Cage Sports, where he would win back the Lightweight title and defend it again against Justin Harrington, before losing it in a TKO loss to Bobby McIntyre. He would have a one fight stint GKO, winning his only fight by TKO, before returning to Cagesports and winning back the Lightweight title against Bryan Nuro, in a unanimous decision. He would fight on Dana White's Contender Series 11, and although he won the fight against Jamall Emmers by knockout, he was not offered a UFC contract.
Return to UFC
Although he did not earn a direct contract after his DWCS fight, he was signed to fight against fellow DWCS alumni Devonte Smith at. He lost the fight knockout in round one. His next fight was on March 9, 2019 at against Grant Dawson. He lost the fight via unanimous decision and was briefly released from the promotion. He was offered a quick return to face Julio Arce on May 18, 2019 at UFC Fight Night 151, despite being released from the promotion after the previous loss. He lost the fight via knockout in the third round and was released once again. After the release, Erosa picked up one win in his native CageSport and was brought back as a late replacement for Kyle Nelson, who had visa issues, against Sean Woodson at. He won the fight via D'arce choke in the third round. This win earned him the Performance of the Night award.
Personal life
Erosa has been married to Alaina Evans since mid-2016. He is non-religious.
