The 25-year-old Irish striker opened the scoring in the 16th minute with a dipping shot before two goals in two second half minutes helped Stokes mark his 100th game for Celtic with a hat-trick.
Leigh Griffiths had a late strike ruled out for offside as the Hoops extended their unbeaten start to the league campaign to 25 games.
The Scottish champions -- thanks to goalkeeper Fraser Forster -- also equalled Aberdeen's Scottish record of 12 consecutive league clean sheets, set in 1970/71, as they got over the disappointment of last week's Scottish Cup exit.
Celtic manager Neil Lennon was delighted to pick up the 150th win of his managerial career.
"I thought the attitude and quality of performance from start to finish was fantastic," Lennon said.
"It makes last week even more of an aberration really when you see the way we played today.
"It was a brilliant team performance and I couldn't be happier with the reaction I got from the players."
St Johnstone manager Tommy Wright praised Celtic.
"It's easy to pick holes in what we didn't do today but I thought Celtic were excellent today," he said.
"They passed it really well and kept us under pressure without creating loads of chances but they looked a really good side today.
"There are things we could have done better in the game and we know that but it's always difficult to come here."
Griffiths was handed his first start for Celtic since joining from Wolves last month and he came close with an early chance as he sent a diving header inches wide after connecting with a Kris Commons clipped pass into the box.
The former Wolves forward had a hand in Celtic's opener in the 16th minute
Virgil van Dijk was allowed space to storm forward from defence and Griffiths cushioned his pass into the path of Stokes, who took a touch before sending a dipping shot into the bottom left-hand corner.
The Celtic fans have become accustomed to seeing Commons' name on the score sheet this season and he nearly added to his tally of 17 league goals in the 25th minute
The Scottish midfielder nicked the ball off the toe of Stefan Johansen before firing a fierce strike that came crashing off the bar before the St Johnstone defence cleared the danger.
St Johnstone had rarely had sight of goal in the match but had a chance to threaten in the second half with David Wotherspoon's shot deflected over the bar before Brian Easton sent his 40-yard effort wide.
However, any hopes Saints had of a comeback were dashed when Stokes scored two goals in two minutes to complete his hat-trick.
The Irishman's first came in the 64th minute when he controlled a scooped pass from Scott Brown with his back to goal and then swivelled to fire a wonderful finish past Mannus.
Stokes didn't have to wait long for his next one as he sealed his hat-trick in the 66th minute.
Dave McKay allowed the Irish striker too much space and he weaved his way into the box before sending a low shot through the Saints defender's legs that beat Mannus at his near post.
Forster had been a virtual spectator for most of the match but had to be alert to stick out a foot to keep out a deflected Nigel Hasselbaink shot in the 79th minute that kept his long shut-out record in the league intact.
Griffiths then thought he had grabbed his first goal for Celtic in the 83rd minute when he lifted a Commons pass beyond Mannus but his effort was ruled out following a tight offside decision.
Source : AFP
Source: AFP