Celtic celebrated the presentation of the Scottish Premier League trophy by delivering a blow to St Johnstone's Europa League qualification hopes.
It was a stroll at Celtic Park from the first minute, when Joe Ledley fired powerfully into the far corner.
Anthony Stokes claimed he had got a touch on a Charlie Mulgrew free-kick that curled in at the back post.
After the break, James Forrest drilled low into the far corner and Frazer Wright added a late own-goal.
Before kick-off, manager Neil Lennon had again failed to rule out a move to Everton to fill the vacancy created by his fellow Celtic old boy David Moyes' summer switch to Manchester United.
But the fact Lennon's team could swat aside the challenge of fourth-top Saints without reaching the heights of their own capabilities might not have done much for his chances of landing the Everton job should he want it.