Jimmy Kimmel better watch his back ... because his 13-year-old nephew, Wesley Kimmel, is banking on taking over Hollywood.

After all ... for his role as Dylan Callahan in the upcoming movie "Red One," the teen's minor contract, obtained by TMZ, unveils his whopping payday of $100K!!!

According to the contract, Wesley pocketed $95K in base pay for his work in the movie and banked an additional $5K for promoting it.

Wesley stars in "Red One" alongside big names Dwayne Johnson, Chris Evans, Kiernan Shipka, and Lucy Liu -- bagging the gig after paying his dues in Disney+ shows such as "The Mandalorian" and "WandaVision."

The movie's official release date is still under wraps ... though considering its festive, action-packed theme, it looks like it'll hit Amazon Prime in the run-up to Xmas.

As for Uncle Jimmy ... he may want to dust off those jokes ... because there may not be enough room for two Kimmels cashing in on Hollywood stardom.