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.
13. Shane Duffy - 5
On for the injured Welsh with 20 minutes to go. Mistake let in Obika for St Mirren's only shot on goal. Photo: Craig Foy - SNS Group
14. Patryk Klimala - N/A
On as a late sub. Too late to make an impact. Photo: Craig Williamson - SNS Group
15. Leigh Griffiths - N/A
Got the last few minutes. No time to impress. Photo: Rob Casey - SNS Group
16. Mohamed Elyounoussi - N/A
Managed to get on the ball a few times despite late introduction. Photo: Craig Foy - SNS Group