Early career Rosas Jr. acquired a record of 5–0 competing exclusively in
Tijuana, Mexico, for the
Ultimate Warrior Challenge Mexico promotion winning all five fights by stoppage inside of two rounds.
Dana White's Contender Series Season Rosas Jr. was then booked to compete on Week 9 of Season 6 of
Dana White's Contender Series on September 20, 2022, against Mando Gutierrez. He would win the fight via a dominant unanimous decision and was awarded a contract by
Dana White thus becoming the youngest fighter to sign a contract with the UFC at the age of 17.
Ultimate Fighting Championship After earning his contract, Rosas Jr. made his UFC debut at
UFC 282 against Jay Perrin on December 10, 2022. At the weigh-ins, Rodriguez weighed in at 137 pounds, one pound over the bantamweight non-title fight limit. His bout proceeded at catchweight and he was fined 20% of his purse which went to Rosas Jr. He lost the fight via unanimous decision. He won the fight by unanimous decision. Rosas Jr. was scheduled to face
Rob Font on September 13, 2025 at
UFC Fight Night 259. However, Rosas Jr. had to withdraw due to an injury and was replaced by
David Martínez. The re-scheduled bout took place on March 7, 2026, at
UFC 326. Rosas Jr. won the fight by unanimous decision. ==Submission grappling career==