The former Inter Milan and Manchester City manager took over the club last summer, but has left after a season in which his side won the Turkish Cup, but finished runners-up in the league and went out in the last-16 of the Champions League.
“As a coach I understand the demands of my club. When I accepted the post of Galatasaray coach the targets were different," said Mancini.
“In these eight months, though I came in during a season that had already been partly damaged, I have done my job with passion and in constant pursuit of victory.
“This was followed by Champions League qualification, the Turkish Cup and second place in the League.
“With regret, I leave Istanbul and the fans, which are both splendid. I give an affectionate goodbye to the President, the team and everyone I have worked with. They worked with talent and loyalty.”
Early reports claim that Mancini agreed to a mutual decision to end his contract early, despite the fact that his quick exit may have cost him a vast financial bonus.
Eurosport Turkey have confirmed the existence of a pay-off clause, and that Mancini will receive no compensation having agreed to leave.
The fact that he agreed to leave without compensation has already sparked speculation that the 49-year-old has another job lined up - and with the hot seat at Southampton vacant following Mauricio Pochettino's move to Tottenham, bookies are already cutting odds on the Premier League-winning manager being in line for a quick return to the English top flight.
Mancini has also been tipped to return to Lazio, where he spent four years as a player and two as a manager, taking the Roman club to the UEFA Cup semi-finals, and winning the Coppa Italia.
- Sports & Recreation