The former UEFA Cup champions are currently ninth in the Turkish championship after eight games, eight points adrift of leaders Bursaspor. Galatasaray have also been eliminated from this season’s Europa League.
Galatasaray held a management board meeting this week after the club’s 4-2 loss at home to Ankaragucu to discuss the situation and said at the time it would announce decisions during the week.
“As a result of mutual talks with technical director Frank Rijkaard... we have decided to part ways as of October 20,” the club said in a statement on its website (www.galatasaray.org).
The Dutchman took the helm at the Istanbul club in 2009 after leaving Barcelona.