Alan Mannus will be rejoining Shamrock Rovers on July 1st 2018.
The former Linfield player left St Johnstone this week and it was expected he was to return to the League of Ireland.
The 35 year old has eight caps for Northern Ireland and featured 69 times for Shamrock Rovers in his last spell.
The Canadian born keeper was the keeper for Rovers in their Europa League run in 2011 and Alain won two League titles with the club.
Image Credit: IrishFA.com