The 18-year-old will take on Jay Perrin on the main card of UFC 282, which is being held at the T-Mobile Arena in Las Vegas.
Rosas Jr already broke records when he signed with the promotion in September after dismantling Mando Gutierrez on Dana White's Contender Series, which saw improve his professional record to a perfect 6-0.
The bantamweight's journey started as a four-year-old alongside his brother, Jesse, with the pair realising they both had the talent to progress in MMA.
"From the ages of 8 to 14 I was fighting people my age, I lost twice and won 25 times," said Rojas Jr. "I also went to Italy to compete for an IMMAF title. After that, I knew I was the best teenager in the world. I made my amateur debut when I was 15, I fought twice and I won both in under one minute.
“I realised that nobody was gonna be on my level as I’d see the professionals, I knew I could beat them even though they were like 7-0. I went pro when I was 17 in Mexico as I couldn’t fight pro in the US until 18.
The teenager, nicknamed 'El Nino Problema', added: “I feel comfortable striking with anybody. I know I’ve still got to get better, but even right now if I was to fight the UFC champion I know I would take him out. Not only win, but finish him. I keep getting better and better, but even at this level I can beat anybody.
“I’m ready to be on the big stage so I’m glad I’m fighting on the pay-per-view card. I’ve been putting a lot of work in and the UFC put me in because I’m going to go and finish this guy. If there’s anybody to put on the pay-per-view card it’s someone like me because I’m a showman. When I fight, I enter the matrix, I fight to win for myself but to also be an entertainer and do some crazy s**t.”
Rosas Jr's confidence is brimming and the young Mexican will feel it even more after receiving a message of support from icon Conor McGregor.
Upon hearing the news that Rosas Jr would become the youngest fighter in UFC history, he posted saying: “That’s incredible! The youngest ever. Good luck young man, in your career with the @ufc.”
