Dick Advocaat is leaving his role as Sunderland head coach after successfully guiding the club to Premier League safety this season.
The 67-year-old Dutchman said he no longer wished to continue a career in club management.
He joined the Black Cats until the end of the season in March, replacing the sacked Gus Poyet, with the side one point above the relegation zone.
"Sunderland has been one of the highlights of my career," he said.
"At certain moments in your life you have to make a decision and I am almost 68 years old now.
"A number of clubs contacted me but the decision was always Sunderland or nobody."
Advocaat wept as he secured Sunderland's Premier League survival with a goalless draw at Arsenal in their penultimate game of the season.
Sunderland chairman Ellis Short said: "Although I am extremely disappointed, I understand and absolutely respect his decision.
"In his brief time here he made a real impact and lifted the club with his experience and enthusiasm. We will always be grateful to him for what he achieved."
The former Netherlands boss, who managed Scottish club Rangers between 1998 and 2002, lost his first Premier League game in charge of Sunderland at West Ham.
|Analysis: BBC Sport's Phil McNulty|
|"The sight of Advocaat tearfully falling into the arms of his old friend and colleague Bert van Lingen in front of thousands of joyous Sunderland fans at Emirates Stadium showed how much keeping up Sunderland meant to him - and how much it has taken out of him.|
But they went on to record three wins and three draws in the remaining eight games to pull clear of relegation, including a 1-0 win over North East rivals Newcastle.
Prior to joining Sunderland, Advocaat won the league title and cup double twice at Ibrox, and league titles in his homeland with PSV Eindhoven and in Russia with Zenit St Petersburg.
He also led Zenit to victory over Rangers in the 2008 Uefa Cup final and Manchester United in the Uefa Super Cup later that year.
Internationally, he has coached the Netherlands twice and also managed United Arab Emirates, South Korea, Belgium, Russia and Serbia.