Murray Davidson got the ball rolling for Saints with his 20th-minute opener and the Perth outfit doubled their advantage by the break courtesy of what seemed to be a Ziggy Gordon own goal.
A third from Matt Kennedy just nine minutes into the second period ended any hopes Accies may have harboured of a comeback.
Tommy Wright’s men remained steadfast at the back to ensure they racked up a fifth clean sheet and added a fourth with 16 minutes left courtesy of a David Wotherspoon tap-in, moving Saints up to fourth.
Hamilton enjoyed the first glimpse at goal after just two minutes but Steven Boyd, perhaps surprised by the break of the ball falling his way, volleyed wide from 12 yards.
Thereafter, it was all St Johnstone.
Tony Watt blasted over and Drey Wright turned a snap-shot wide before Davidson pushed a close-range effort past the post following a Kennedy free-kick that was nodded down by Jason Kerr.
The pressure finally paid off after 19 minutes.
Wright beat his marker on the right edge of the box before drilling a low cross into the six-yard box seeking out Watt.
Accies goalkeeper Gary Woods parried the centre out but only succeeded in finding Davidson, who made the most of the chance from six yards.
The goal gave the already-buoyant Saints even more confidence and they piled men forward in search of the second.
They finally got it in fortuitous fashion nine minutes from the break.
Wright shaped to fire in a cross from the right and the ball appeared to flash into the back of the net via a deflection off the shoulder of the unlucky Gordon.
Wright swerved a shot just over the bar in the 53rd minute as the second half continued in the same vein with the home side attacking at will.
And just two minutes later, they extended their lead to seal the points.
Wotherspoon took advantage of a wide open visiting rearguard to stroke a pass beyond the central defenders for Kennedy to stroll onto.
The winger made no mistake as he calmly slipped his shot under Woods’ despairing dive and into the net.
Kennedy struck the bar with a fierce drive before Saints added a fourth in the 74th minute.
Delphin Tshiembe attempted a back pass but Kennedy read it and darted in on goal before unselfishly trying to find the supporting Chris Kane.
As the ball squirmed out of a challenge, Wotherspoon hammered it into the empty net.
Rakish Bingham’s header from a Dougie Imrie corner four minutes from time landed on top of the crossbar but it was Hamilton’s only meaningful effort on goal all game in a dismal display.