The former Hibernian striker was the star of the show as he put the visitors to the sword on Sunday, opening the scoring after 15 minutes before two goals in three second-half minutes completed Neil Lennon's 150th victory as Celtic manager.
St Johnstone failed to register a single shot on target as Celtic goalkeeper Fraser Forster recorded his 12th consecutive league clean sheet, equalling a 43-year-old Scottish top-flight record.
Stokes got the first when he latched onto Leigh Griffiths' flick and fired home from the edge of the box.
St Johnstone could not get a foothold in the game and it was no surprise when the Republic of Ireland international put the hosts 2-0 up after 64 minutes, controlling Scott Brown's scooped cross and rifling past Alan Mannus from eight yards out.
And Stokes completed the third hat-trick of his Celtic career two minutes later he as he cut in from the left and hit a right-footed effort that beat Mannus at his near post.
The result sees Celtic extend their seemingly unassailable lead over Aberdeen at the top of the table, while St Johnstone remain in sixth, one point ahead of Hibernian.
