Goal's Tom Maston reported the news.
The 33-year-old moved to Istanbul in 2013 after a successful spell with Inter Milan and led Galatasaray to two Turkish league titles. The Yellow-Reds have struggled since the 2014-15 campaign, however.
The timing of the Netherlands international's departure comes as a shock―earlier this week, fans thought he reassured them rumours of a move were unfounded when he tweeted this:
Even at the age of 33, Sneijder remains an excellent option as an attacking midfielder. He led the Turkish league in assists last season with 15 and added five goals, showing no signs of slowing down.
As a free agent, he could be a tremendous value signing for a number of clubs in Europe, or he could opt to take his talents to the MLS, as so many veteran players have done before him.