David Zitelli repaid manager Alex McLeish for restoring him to the Hibs line-up by scoring two vitals goals that prevented St Mirren causing a surprise at Easter Road.
Hibs had eased into the lead thanks to a Frank Sauzee free-kick. But a Rickie Gillies double either side of half-time gave the second-bottom visitors a taste of victory before Zitelli struck twice in two minutes.
Russell Latapy added the fourth to ensure that Hibs leapfrogged Rangers back into second place in the Scottish Premier League.
St Mirren made a single change from the side that had lost 3-0 to Kilmarnock at Hampden Park on Tuesday night, with Iain Nicolson replacing Gary Bowman.
Hibs were back to full strength again as they welcomed back midfielders John O’Neil and Mathias Jack from suspension. Zitelli replaced Dirk Lehmann up front.
The French striker almost made an immediate impression with a deep cross to the back post but Stuart Lovell’s first-time effort was brilliantly clawed off the line by goalkeeper Ludovic Roy.
Tommy Turner then did well to clear the ball from in front of his own goal after Lovell headed the ball into Zitelli’s path.
The breakthrough finally came after 16 minutes. O’Neil and Gillies went for a ball on the edge of the St Mirren box and the ball slid back into the arms of Roy. The Hibs midfielder immediately claimed for a pass back and Kevin Toner awarded a free kick 16 yards out.
It was a controversial decision as at first it looked like O’Neil had himself touched the ball but television replays suggested that the referee had got it right.
St Mirren got their wall wrong and, when the ball was tapped into the path of Sauzee, the Frenchman curled it into the far corner.
Lovell stole into the box to curl a volley just wide as Hibs threatened to overwhelm the visitors. St Mirren at last created a chance when Mark Yardley wriggled past two defenders and into the box but the big striker toe-poked the ball wide under pressure.
They went one better moments later when Graham Fenton found himself behind the Hibs defence. Gary Smith appeared to clip the former Blackburn Rovers striker’s heel from behind and Gillies stepped up to send Nick Colgan the wrong way from the spot.
Hibs were further stunned six minutes after the break. Sergei Baltacha broke from the back and set up Gillies 20 yards out. The midfielder’s drive deflected off O’Neil, over Colgan and into the net.
Hibs were stung into action and Latapy played the ball to Zitelli inside the box after 59 minutes. The striker held off Baltacha before sliding the ball in off the post.
Two minutes later, Paul Rudden dallied on the ball on the edge of his own box and Zitelli stole in to power the ball in off Roy.
Latapy settled the game after 80 minutes after he lost the ball to Gillies then won it back before driving low into the far corner.
Hibs: Colgan, Fenwick, Sauzee, Gary Smith, Lovell, O’Neil, Latapy, Jack, Laursen, Paatelainen, Zitelli. Subs: Franks, Andrews, Lehmann, Murray, McManus.
St Mirren: Roy, Nicolson, Turner, Baltacha, Walker, Kerr, McKenzie, Rudden, Gillies, Fenton, Yardley. Subs: Scrimgour, McGarry, Bowman, Dagnogo, Quitongo.
Referee: K Toner.