The Netherlands international praised his former manager during an interview with the Portuguese daily newspaper O Jogo.
“Mourinho will come back stronger, I have said this many times: He is a good coach, but also good manager,” Sneijder told the Portuguese daily newspaper O Jogo.
“It would be no surprise if he wins more titles at Chelsea.”
Chelsea currently sit in 15th place in the Premier League and the Blues boss is under intense pressure following a defeat at home to Liverpool.
Sneijder played under Mourinho while at Inter Milan. The Netherland’s international won the UEFA Champions League and Serie A under the Portuguese manager.
The 31-year-old has provided two assists and scored two goals in 14 appearances for Galatasaray this season.
The Lion’s were defeated by Benfica in the Champions League yesterday evening and take on Rizespor in the league on Saturday.
Chelsea are up against Dinamo Kiev tonight in the Champions League and travel to Stoke City this weekend.