Born on 23 February 1992 in São José dos Campos, Brazil, Casemiro came through the youth academy at São Paulo FC, where he captained junior sides from the age of 11. He made his Série A debut in July 2010 and scored 11 goals in 111 appearances for the club before catching the attention of European scouts.
In January 2013, Real Madrid brought him in on loan, and the move was made permanent shortly after. Following a productive season-long loan at Porto in 2014–15, he returned to Madrid and established himself as first choice under Zinedine Zidane. Over nine years at the Santiago Bernabéu, he won five UEFA Champions League titles, three La Liga titles, three FIFA Club World Cups, and a Copa del Rey, among other honours. Highlights include a goal in the 2017 Champions League final against Juventus and being named Man of the Match in the 2022 UEFA Super Cup.
A hard-tackling, physically strong defensive midfielder with sharp positional awareness and reliable distribution, Casemiro joined Manchester United in August 2022 for a reported fee of around £70 million. In his first season, he scored the opening goal in the EFL Cup final victory over Newcastle United and won the Alan Hardaker Trophy for his performance.
A full international since 2011, Casemiro has earned over 75 caps for Brazil. He featured at the 2018 and 2022 FIFA World Cups and won the 2019 Copa América, also finishing runner-up in 2021. At club level, he is currently part of the Manchester United squad as his contract runs toward the end of the 2025–26 season.