In a statement, Flamengo said the club acquired Isla as the 32-year-old right back signed a contract until December 2022.
Isla is an experienced defender who played for Italian clubs Udinese and Juventus and French team Olympique Marseille. He was a Fenerbahce player from 2017-2020 but became a free agent in June.
Isla helped Juventus win Italian top-flight Serie A titles in 2013, 2014 and 2016. He had 115 caps for the Chilean national team to bag the Copa America trophy twice in 2015 and 2016.