The corresponding fixture at the end of last season had ended in a 3-3 draw but following a low-key goalless first half a similar scoreline didn't look likely.
Celtic made the breakthrough 10 minutes after the break when a defensive lapse from Steven Anderson allowed Kris Commons to send Anthony Stokes clear and the Irish striker rounded Alan Mannus to fire Celtic in front.
St Johnstone's Dave Mackay had a penalty appeal turned down before the defender was shown a red card for conceding one after he clipped the legs of substitute Derk Boerrigter as he bore down on goal
Nir Biton stepped up to convert the 76th minute spot-kick for his first goal for the club.
Callum McGregor completed the scoring in the 84th minute following a goalkeeping howler as Mannus somehow let his low shot squirm through his fingers and over the line as new manager Ronny Deila's first competitive league match in charge ended in victory.
The win leaves Celtic in fourth having played a game less than leaders Dundee United who visit Celtic Park on Saturday.
St Johnstone may have sold last year's top scorer Stevie May to Sheffield Wednesday but chairman Steve Brown was still afforded a cheer as he paraded the Scottish Cup before kick-off.
May's absence left Steven MacLean to lead the line for Saints while Craig Gordon, in his first Scottish top flight match since May 2007, took over in goal for Celtic following Fraser Forster's transfer to Southampton.
Celtic were presented with the first real chance of the match when Commons slipped in James Forrest but the winger dragged his effort from the edge of the box wide.
A lack of concentration from Anderson allowed Celtic to take the lead in the 55th minute.
The St Johnstone defender dwelled too long on the ball allowing Commons to win possession with a sliding challenge
Stokes picked up the ball and rounded keeper Mannus before sending a shot in off the post from a tight angle.
St Johnstone were appealing for a penalty soon after when Mackay appeared to be felled in the box following a clumsy challenge from Virgil van Dijk but referee John Beaton waved away their protests.
Minutes later Mackay's match was over when he was shown a straight red as sub Boerrigter collapsed in the box following a collision with the Saints player with Biton converting the resultant penalty.
The Israeli then turned provider as he picked out McGregor whose low shot went through the legs of a defender before somehow squirming through the fingers of Mannus and over the line.
Dundee United, though, should provide stiffer opposition as they made it two wins out of two following a 1-0 victory over Motherwell and another potential title rival Aberdeen got their campaign on track, after United defeated them 3-0 on the opening day, as they beat Kilmarnock 2-0.
Source : AFP
Source: AFP