Marcelo, a five-time Champions League Cup winner for Real Madrid, has signed a contract with Fluminense, the Brazilian club's press office reports.
Marcelo, who started his career at Fluminense, played for Olympiacos this season, scoring three goals in 10 games. The 34-year-old Brazilian terminated his contract with the Greek club by mutual agreement in February.
Marcelo had previously played for Real Madrid for 15 years and won 25 trophies, including five UEFA Champions League titles.
It was previously reported that Marcelo's long-term Real Madrid partner Cristiano Ronaldo wants to see the Brazilian in his new club, Saudi Arabia's Al-Nassr.