Diogo “Baby Shark” Reis

Diogo Reis, widely known as “Baby Shark” to his legion of supporters, is a prominent Brazilian Jiu-Jitsu black belt hailing from Manaus, Brazil.

Born and raised in Manaus, Reis grew up in a lower-middle-class family – his mother a nurse technician, his father a fishmonger. He stayed out of trouble as a kid, though he’s quick to admit he struggled in the classroom, even failing the second and third grades. Soccer was his first love, but everything changed at the age of 10, when he watched his brother train at coach Alexandre Oliveira’s academy and decided to give Brazilian Jiu-Jitsu a try. Granted a scholarship to train, Reis had found his calling.

A few years later, his talent caught the eye of Melqui Galvao – one of the region’s premier developers of young grappling talent – who spotted him at a tournament and invited him to train under his mentorship.

From there, Reis’ ascent was meteoric.

As a juvenile, he completed the rare “grand slam” of the sport, capturing the IBJJF World, Pan, Brazilian, and European Championships. The accolades came despite serious financial hurdles; to afford travel from Manaus to southern Brazil and the United States, Reis sold raffle tickets and leaned on the support of friends.

His rise only accelerated. “Baby Shark” had his first tournament at black belt in December 2020 and was promoted to the rank just days later – roughly seven months after earning his brown belt. He racked up major titles over the next couple of years, but it was his triumph at the 2022 ADCC World Championship in the 66-kilogram division that turned him into a superstar. He reinforced his dominance by defending that crown in 2024.

That elite pedigree earned him a contract with ONE Championship in 2024, and he wasted little time making history on the global stage. In December 2025, Reis claimed the vacant ONE Flyweight Submission Grappling World Title by defeating one of the world’s top competitors in his weight class, Daiki Yonekura.

Capping a monumental run, Reis was named ONE Championship’s Submission Grappler of the Year for 2025. He may be a World Champion in his prime now, but “Baby Shark” is just getting started.