Two first-half goals from Billy McKay, who later spurned a chance to claim his hat-trick when he missed from the penalty spot, were sufficient enough to overcome a Hearts side that finished with 10 men when Jamie Hamill saw red.
Aberdeen had the better chances but could not find a way through in a 0-0 draw against St Johnstone at Pittodrie.
The result means St Johnstone stayed a point above their opponents in the early league standings.
Hibernian remained winless against Ross County after playing out an underwhelming stalemate against the men from Dingwall at Easter Road.
The Hibees have now played County six times, spanning four years, and have yet to register a victory.
Partick Thistle heaped yet more pressure on under-fire St Mirren boss Danny Lennon as they handed him his fourth defeat from five games this season.
The Buddies looked set to collect their first three points of the season after Kenny McLean had given them an early second-half lead.
But Kallum Higginbotham and Ross Forbes struck twice in the final 10 minutes to secure a 2-1 win ensure Lennon was treated to another round of boos from the furious Paisley public at the final whistle.
In the early game Anthony Stokes' 87th-minute free-kick gave Celtic a 1-0 victory over Dundee United.