A former player with the Greenock club, Imrie returns to Cappielow from Livingston, where he was a first-team coach.
Director Graham Bar told the club website: "It is great to be able to welcome Dougie Imrie to the club as our new first-team manager.
“Dougie was the stand-out candidate during the recruitment process and his vision, ambition and enthusiasm for the club was clear to see.
“What was also clear to us in the interview process is that Dougie is both committed and determined to bring success to Morton, both in the short and long term."
