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.
9. Tom Rogic - 8
Got Celtic off the mark with a quality turn and finish and showed good energy and appetite throughout. Photo: Craig Foy - SNS Group
10. Albian Ajeti - 6
Linked play well in the first half without ever looking a threat. Subbed off midway through the second half. Photo: Craig Williamson - SNS Group
11. Odsonne Edouard - 7
Stepped up to take the penalty and expertly despatched to score for the fifth conseutive game. A constant threat to the Saints defence with movement and touch. Photo: Craig Williamson - SNS Group
12. Ryan Christie - 7
Off the bench to score Celtic's third with a lovely finish with the outside of the boot. Photo: Craig Foy - SNS Group