A first half strike from Tom Rogic gave Neil Lennon’s side a half-time lead, before a three goal burst in four minutes late in the second half finished off the Saints.
Odsonne Edouard struck the second from the penalty spot on 79 minutes before substitute Ryan Christie added a third on 82 with David Turnbull finishing off the scoring a minute later.
St Mirren rarely troubled the Celtic goal as the defending Scottish Premiership champions wrapped up a third consecutive victory.
Here’s how the Celtic players rated in the 4-0 rout ...
Player ratings scale - 10: One of the best performances you've seen. 9: Outstanding. 8: Very good. 7: Good. 6: Average. 5: Poor, 4: Very poor. 3: A terrible day at the office. 2: Abysmal. 1: One of the worst performances you've seen.