Liam Henderson opened the scoring with a terrific free-kick before John McGinn increased the lead against his former club.
Stevie Mallan pulled one back with a free-kick of his own before half-time.
Anthony Stokes played the final 20 minutes and marked his Easter Road return with a late third for the hosts.
Alan Stubbs, whose side moved two points clear of Falkirk, resisted the temptation to start Stokes following his arrival on loan from Celtic given the Irishman had not played first-team football since August.
His opposite number, Alex Rae, handed a debut to Rocco Quinn, who had arrived from Ross County since their last action more than a fortnight ago.
The pre-match headlines were about Stokes, but it was another on-loan Celt who brought the Hibs fans to their feet.
Henderson was brought down on the edge of the box by Jack Baird and though referee Don Robertson initially allowed the advantage, he brought it back.
The midfielder got back to his feet and whipped a wonderful shot into the top corner. It was an outstanding effort that arched over Buddies goalkeeper Jamie Langfield.
Hibs dominated proceedings for large spells and should have doubled their lead when Jason Cummings latched on to a long ball which dropped over his shoulder leaving him one-on-one with Langfield, who stood tall to deny the Easter Road top scorer.
Cummings and January signing Chris Dagnall tested Langfield, who was single-handedly preventing the roof from caving in.
The veteran could only stem the flow for so long and after good set-up play by Cummings, McGinn stroked home.
St Mirren threatened very occasionally but gave themselves a lifeline with the last kick of the opening half and it was their main threat who provided it.
Stevie Mallan has a penchant for the spectacular and he found the bottom left of Mark Oxley's goal with a superb free-kick.
The pattern of Hibs dominance continued after the interval and Paul Hanlon had one header saved and another cleared off the line while a deflected McGinn drive just cleared the crossbar.
Stokes took his second Easter Road bow with 20 minutes to play and soon tapped home after good set-up play by fellow-sub James Keatings.
Hibernian moved to within two points of Rangers at the top of the Championship with a comfortable victory over St Mirren.