Michael Musumeci Jr. (born July 7, 1996) is an American submission grappler and Brazilian Jiu-Jitsu black belt competitor.

[12][d] He began training Brazilian jiu-jitsu (BJJ) at age 4 along with his sister Tammi at Fatjo's Martial Arts Academy under coach Fernando "Cabeça".

[16] In 2017 Musumeci won the UAEJJF World Pro at black belt in the 62 kg weight class.

Musumeci made his Who's Number One debut on March 26, 2021, where he submitted Marcelo Cohen with an armbar from the triangle choke position.

[19] Musumeci was then invited to compete in the inaugural WNO Championships event, taking part in the tournament for the promotion's Lightweight title.

[20] Musumeci faced Gabriel Sousa in the opening round and was submitted by north-south choke, removing him from the competition.

[25] After the conclusion of the match, both Martinez and his coach Eddie Bravo confronted Musumeci as they exchanged heated words on the mat.

[30] Musumeci defended the WNO Bantamweight title against Estevan Martinez on January 21, 2022, winning by unanimous decision.

[36] Musumeci faced Cleber Sousa for the inaugural ONE Flyweight Submission Grappling World Championship on October 1, 2022, at ONE on Prime Video 2.

[44] Musumeci defended his flyweight submission grappling title against Jarred Brooks at ONE Fight Night 13 on August 5, 2023.

[48] In February, 2024, Musumeci announced that he was leaving Pedigo Submission Fighting and would be joining Cobrinha BJJ to train under Rubens Charles Maciel.

[53] Musumeci was set to challenge Kade Ruotolo for his ONE lightweight submission grappling title on September 6, 2024, at ONE 168: Denver.