The Northern Irishman took over from Alan Stubbs last September and managed to successfully keep the club in the top flight after a play-off final victory over Dundee United.
After originally saying he planned to stay with the Buddies, it soon emerged that Kearney was heading for the exit door and was told to stay away from the club's return to pre-season training.
Kearney signed a three-year deal upon his arrival at the club but continued to travel to and from Ballymoney as his family remained across the Irish Sea.
After much speculation, the St Mirren board confirmed Kearney's departure on Wednesday afternoon.
A short statement on the club's website read: "The board can confirm that Oran Kearney has left the Club by mutual consent.
"The club wish to thank Oran for his time in charge and wish him every success in the future."