The Northern Irishman has signed a deal that will take him up to the end of the 2023-24 campaign.
Browsing: Neil Lennon
Lennon, who returned to manage Celtic for a second time after Brendan Rodgers moved to Leicester in February 2019, has been under pressure all season but had previously maintained he would not resign.
The Nigeria international had been linked with a return to Easter Road, with St Johnstone also interested in the former Celtic man.
Ambrose was left frustrated in the January transfer window when his proposed move to Blackburn Rovers fell through due to the FA refusing the player a work permit
Ambrose was taken out of the firing line for his own good by Rodgers in August after being booed by some Celtic supporters in Dublin after scoring an own goal in a friendly match against Barcelona