Neil Lennon quit as manager of Celtic after a successful four years in charge of the Glasgow giants, his agent announced.
Martin Reilly, his agent, said: “Four years is a good spell to be manager of a club like Celtic but now Neil wants to look ahead to the next chapter of his career.”
Under Lennon Celtic have won the Scottish title for the past three years.
The 42-year-old former Northern Ireland international was Celtic captain under Gordan Strachan, taking over from Tony Mowbray as boss of the Hoops' in March 2010.
BBC Scotland quoted Lennon as saying: “I have parted company with Celtic. I can't thank Peter Lawwell and the board enough for their backing and support.
“The club are in a very strong position and I wish the fans and the club all the very best for the future.”
As well as success in the league Lennon has also helped Celtic claim two Scottish Cup wins and masterminded their run to the last 16 of last season's Champions League.
That European campaign also included the famous Parkhead win over Barcelona and former Leicester midfielder Lennon is now expected to continue his career in England.
But despite being linked with the vacant managerial positions at Norwich and West Brom, Reilly insists his client has not agreed to any job offer yet.
He added: “He has nothing lined up. He just feels now is the time to move on to the next challenge.”