Lawrence Shankland's 12th goal of the season saw Hearts dispense with St Johnstone on Craig Levein's return to Tynecastle. The visiting manager was back at his old workplace in a coaching role for the first time since 2019 and left with a defeat.
Liam Boyce met a low cross on 60 minutes and his shot landed in the net via a deflection off Shankland's leg to separate the teams and give Hearts three successive Premiership wins for the first time since January 2022. Added to victories over Livingston and Motherwell before the international break, it was another valuable three points for Steven Naismith's side.
Saints were undefeated in their previous two games since Levein and assistant Andy Kirk took charge. They forced some important saves from the Hearts goalkeeper Zander Clark during the 90 minutes and would have left Edinburgh cursing his work.
It was the hosts who started strongest, though. An early flowing Hearts attack ended with Alex Cochrane forcing a superb diving save from the St Johnstone goalkeeper Dimitar Mitov. Moments later, the Bulgarian was down to his left to push away Boyce's header following a corner.
St Johnstone would have scored first in this match but for Clark's point-blank save on 23 minutes. The Hearts goalkeeper - facing his former club - reacted instinctively to beat away Luke Robinson's first-time effort after a ricochet from a cross ball near the six-yard line.
The hosts controlled much of the ball during the opening 45 minutes, although clear scoring chances did not materialise too often. Clark was at full stretch to turn Matthew Smith's cross away for a corner after the break. The keeper then parried a powerful drive from Max Kucheriavyi as Saints probed at the Hearts back line.
Increasing nerves among the home support eased on the hour mark when the deadlock was broken. A patient passing Hearts move saw the ball worked from side to side through midfield, and eventually found Cochrane high on the left wing. His low cross was converted by Boyce via a ricochet off Shankland - which prompted St Johnstone to appeal that the Tynecastle captain was offside and interfering with play.
The goal stood and helped calm down those who had become slightly impatient. Without being hung-ho, Hearts pursued a second goal during the final 30 minutes with St Johnstone looking dejected. As it was, one was enough for victory.
Here are the Hearts player ratings from Tynecastle:
1. GK: Zander Clark 7/10
Back from Scotland duty to face his former club. Instinctive stop to deny Robinson on 23 minutes. Also pushed away Smith's cross as it threatened to drop into the net in the second half.
2. RCB: Stephen Kingsley 8/10
Solid in defence and comfortable stepping out with the ball. Strong display.
3. CB: Frankie Kent 7/10
Good display by the Englishman who dominated both in the air and on the ground.
4. LCB: Kye Rowles 7/10
Assured in challenges and used the ball well on the left of the back three.