Paul Hanlon and Eoin Doyle were on target as Hibs made it back-to-back wins in the Scottish Premier League.
The home side rarely threatened in the first half but a header from Hanlon looped over St Johnstone keeper Alan Mannus on the stroke of half-time.
Doyle knocked in a 53rd-minute rebound from six yards after Mannus had stopped his initial effort.
With Hibs growing in confidence, St Johnstone fell out of the game and could not find a way back.
Pat Fenlon's side were far from their best in the opening 45 minutes but there is a new-found steel to the men in green, who move up to second in the table on seven points.
The visitors welcomed back striker Rowan Vine and Gregory Tade from suspensions and had Hibs pinned back for most of the first half.
With central midfield duo Gary Deegan and Jorge Claros sitting deep, the home side were very slow out of the blocks and could not service in-form striker Leigh Griffiths, who had scored twice in last weekend's success at St Mirren.
Hanlon made a good sliding block in front of his own goal as Liam Craig fired in a low shot after his free kick was blocked by the defensive wall.
St Johnstone's Nigel Hasselbaink then fluffed his shot after a positive burst into the penalty area, allowing Hanlon to clear again.
Deegan was caught dithering in possession and was relieved to see defender James McPake recover the situation by ushering the powerful Tade away from goal.
The Hibs captain again thwarted the St Johnstone striker when Tade came charging in from the left only to take a clumsy touch which gave McPake the opportunity to make an excellent sliding tackle.
St Johnstone full-back Dave MacKay fired wide from 30 yards and Hasselbaink should have done better when he over-hit a cross for the unmarked Vine at the back post.
With the Perth continuing to press, Murray Davidson cleverly steered the ball towards Vine with his chest but the striker's shot from the edge of the penalty box was smothered by Hibs keeper Ben Williams.
Completely against the run of play, Hibs snatched the lead when Hanlon rose to meet a Griffiths corner on 45 minutes.
The defender's header smacked down into turf and bounced over Mannus and had clearly crossed line by the time Callum Davidson had executed an acrobatic clearance.
The second half opened with Paul Cairney jinking into the penalty area but Steven Anderson made a great lunging block just as the Hibs midfielder was about to pull the trigger.
Hibs doubled their lead when Doyle knocked in his first goal of the season from close range.
Griffiths did well to race in from the left and pick out his strike partner with a low cross and while Mannus made a great save to keep out Doyle's first shot the Saints keeper could do nothing about the follow-up effort.
Tade had a great chance to reduce the deficit when McPake was caught out by a long ball over the top but Williams was out swiftly to make an impressive sprawling save near the penalty spot.
At the other end, McPake headed narrowly wide of the target after throwing himself at a David Wotherspoon corner.
Hibs worked the ball from one penalty box to the other with some neat passing which culminated with Mannus saving comfortably from Cairney's cute dink.
The same player then saw a shot blocked by a blue-shirted defender as the ball broke his way from a corner.
St Johnstone faded as an attacking force as Hibs improved their passing game, although Craig did lash in a dipping shot from 20 yards that Williams was equal to.
And the impressive Williams was right behind a header from Saints substitute Peter Pawlett in the closing minutes.
Substitution Eoin Doyle goes off and Ross Caldwell comes on.
Free kick awarded for an unfair challenge on James McPake by Sean Higgins.
Shot by Rowan Vine. Save by Ben Williams.
Outswinging corner taken by Sean Higgins, save made by Ben Williams. Inswinging corner taken from the right by-line by Steve May, clearance by Paul Hanlon.
Free kick awarded for a foul by Eoin Doyle on David MacKay. Direct free kick taken by Liam Craig.
Strike comes in from Paul Cairney from the free kick, blocked by Callum Davidson. Inswinging corner taken right-footed by Leigh Griffiths, save by Alan Mannus.
Substitution (St Johnstone) makes a substitution, with Steve May coming on for Gregory Tade.
Paul Cairney takes a shot. Save by Alan Mannus. Sean Higgins challenges Alan Maybury unfairly and gives away a free kick.
Free kick taken by Liam Craig.
Booking The referee cautions David Wotherspoon for unsporting behaviour.
Unfair challenge on Rowan Vine by David Wotherspoon results in a free kick.
Unfair challenge on Eoin Doyle by Steven Anderson results in a free kick. David Wotherspoon restarts play with the free kick. James McPake takes a shot. Save made by Alan Mannus.
Gregory Tade fouled by James McPake, the ref awards a free kick. Free kick taken by Murray Davidson. Corner taken left-footed by Murray Davidson from the left by-line, Frazer Wright produces a headed effort from deep inside the six-yard box which goes wide of the right-hand upright. Unfair challenge on David MacKay by Eoin Doyle results in a free kick. Alan Mannus takes the direct free kick.
A cross is delivered by Callum Davidson.
The referee blows for offside. Alan Mannus takes the indirect free kick.
Inswinging corner taken right-footed by David Wotherspoon, James McPake produces a header from deep inside the six-yard box which goes wide of the right-hand post.
David MacKay delivers the ball, Gregory Tade concedes a free kick for a foul on James McPake. Ben Williams takes the free kick.
Alan Maybury takes the direct free kick.
Substitution Nigel Hasselbaink goes off and Sean Higgins comes on.
Booking David MacKay is cautioned.
Unfair challenge on Leigh Griffiths by David MacKay results in a free kick.
Free kick awarded for an unfair challenge on Rowan Vine by Paul Hanlon. Liam Craig restarts play with the free kick.
Corner taken short by Rowan Vine. Leigh Griffiths has an effort at goal from close in which goes wide right of the target. The referee blows for offside. Alan Mannus takes the free kick. Rowan Vine is ruled offside. Ben Williams takes the free kick.
Leigh Griffiths produces a cross.
A cross is delivered by David MacKay, James McPake makes a clearance.
Inswinging corner taken left-footed by David Wotherspoon, Frazer Wright makes a clearance. The ball is sent over by Leigh Griffiths.
Leigh Griffiths produces a cross, clearance by Steven Anderson.
Substitution (St Johnstone) makes a substitution, with Peter Pawlett coming on for Patrick Cregg.
Corner taken by David Wotherspoon from the left by-line, Alan Mannus makes a save.
The offside flag is raised against Gregory Tade. Ben Williams takes the direct free kick.
Eoin Doyle gives away a free kick for an unfair challenge on Patrick Cregg. Alan Mannus takes the direct free kick.
52:24 Goal scored
Goal - Eoin Doyle - Hibernian 2 - 0 St J'stone Eoin Doyle fires in a goal from close in to the top right corner of the goal. Hibernian 2-0 St Johnstone.
Paul Cairney sends in a cross, Steven Anderson manages to make a clearance. Leigh Griffiths takes a shot. Save by Alan Mannus. Free kick awarded for a foul by Gregory Tade on James McPake. Ben Williams restarts play with the free kick. Eoin Doyle takes a shot. Save by Alan Mannus.
Effort on goal by Jorge Claros from long range goes over the bar. Free kick awarded for a foul by Leigh Griffiths on Patrick Cregg. Callum Davidson takes the free kick.
Unfair challenge on Tim Clancy by Nigel Hasselbaink results in a free kick. Ben Williams restarts play with the free kick.
Leigh Griffiths challenges Murray Davidson unfairly and gives away a free kick. David MacKay takes the free kick.
The referee gets the second half started.
45:00 +1:11 Half time
Half Time The whistle is blown to end the first half.
44:27 Goal scored
Goal - Paul Hanlon - Hibernian 1 - 0 St J'stone Paul Hanlon fires in a goal from close in to the top right corner of the goal. Hibernian 1-0 St Johnstone.
Inswinging corner taken by Alan Maybury,
David Wotherspoon produces a right-footed shot from just outside the box that goes wide right of the target.
Free kick awarded for a foul by Nigel Hasselbaink on Jorge Claros. Tim Clancy takes the free kick.
Corner taken by David Wotherspoon, clearance by Steven Anderson.
The ball is swung over by Patrick Cregg, Ben Williams makes a save.
Jorge Claros challenges Gregory Tade unfairly and gives away a free kick. Callum Davidson takes the free kick. Rowan Vine is ruled offside. Indirect free kick taken by Ben Williams.
Liam Craig crosses the ball, save made by Ben Williams.
Rowan Vine takes a shot. Save by Ben Williams.
A cross is delivered by Nigel Hasselbaink.
Free kick awarded for an unfair challenge on Murray Davidson by Eoin Doyle. Direct free kick taken by Murray Davidson.
Shot from just outside the box by Rowan Vine goes over the bar.
David MacKay has an effort at goal from just outside the box which goes wide of the left-hand upright.
Free kick awarded for an unfair challenge on Jorge Claros by Murray Davidson. Paul Hanlon takes the free kick.
Inswinging corner taken by Liam Craig from the left by-line played to the near post, Murray Davidson has a header from close range and clears the crossbar.
Patrick Cregg concedes a free kick for a foul on David Wotherspoon. Tim Clancy takes the direct free kick.
Corner taken left-footed by Liam Craig from the left by-line to the near post, clearance made by Paul Cairney.
Foul by Gregory Tade on James McPake, free kick awarded. Ben Williams restarts play with the free kick.
The ball is delivered by Liam Craig.
Free kick awarded for an unfair challenge on Murray Davidson by Gary Deegan. Strike on goal comes in from Liam Craig from the free kick. Inswinging corner taken from the right by-line by Liam Craig, clearance by Alan Maybury. Nigel Hasselbaink takes a shot. Inswinging corner taken from the left by-line by Callum Davidson.
A cross is delivered by Liam Craig, Eoin Doyle manages to make a clearance.
James McPake concedes a free kick for a foul on Rowan Vine. Callum Davidson takes the direct free kick.
The ball is sent over by Rowan Vine, James McPake makes a clearance.
Eoin Doyle takes a shot. Callum Davidson gets a block in.
The ball is crossed by Callum Davidson, James McPake makes a clearance.
Free kick awarded for an unfair challenge on Tim Clancy by Liam Craig. Tim Clancy takes the direct free kick.
Rowan Vine is flagged offside by the assistant referee. Ben Williams takes the free kick.
The ref blows the whistle to start the match.
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