Allan Nascimento built his professional mixed martial arts career around the grappling craft that carried him from São Paulo gyms to the UFC. Nascimento, the Brazilian flyweight known as "Puro Osso," died on August 3, 2026, at 34, the UFC announced.

He was born Allan Alves do Nascimento in São Paulo on September 11, 1991. A schoolmate suggested muay Thai when he was 15, and the sport soon became the direction of his life. As Nascimento explained to Sherdog, the nickname Puro Osso, or Just Bones, came from his slight build when he joined an academy. It followed him from the Brazilian regional circuit to the sport's largest stage.

Nascimento made his professional debut in 2011. He built experience at home and abroad, fighting in Brazil, the United States, and Japan. His 2016 run with RIZIN put his long frame and active submission game before a new international audience. A Brazilian jiu-jitsu black belt under Master Barbosa, he carried that ground craft into the striking tradition of Chute Boxe Diego Lima.

His route into the UFC unfolded over years rather than a single breakthrough. Nascimento appeared on Brazil's edition of Dana White's Contender Series in 2018, then secured a UFC contract after a first-round submission in July 2021. Before his October 2021 debut, he told MMA Fighting that the opportunity had arrived when he was ready for the world's biggest promotion.

The Octagon gave Nascimento a wider platform for the methodical grappling that defined his work. In May 2022, he earned his first UFC victory by controlling Jake Hadley through three rounds, with every judge scoring the bout 30-27. He followed it by submitting Carlos Hernandez in the first round in January 2023. Across six UFC appearances, he collected four victories and two Performance of the Night bonuses.

Nascimento also kept revising how he trained. Before returning to competition in May 2025 after 868 days away, he told MMA Fighting that yoga had helped him balance physical preparation with the mental demands of a fight plan. He returned with a decision victory over Jafel Filho and later submitted Cody Durden, adding two more wins to his UFC record.

Nascimento's career now sits in the record of a São Paulo teenager who turned a schoolmate's suggestion into international work: Brazilian regional bouts, a RIZIN stage, six UFC appearances, and four Octagon victories. The submissions, the patient route into the UFC, and the training partnerships at Chute Boxe give Puro Osso a distinct place in Brazil's flyweight story.