Connor Ronan's impressive strike sealed an impressive capital win against Hibs to extend St Mirren's unbeaten run in 2022.
The Buddies arrived in Edinburgh knowing a victory in Leith would bring them to within just two points of Shaun Maloney's side.
And they more than matched the hosts in an eventful first half, with Jordan Jones, Jay Henderson and Alex Greive all seeing efforts well-saved by in-form keeper Kevin Dabrowski.
Hibs raced out of the traps in the second half, with Jak Alnwick producing two superb saves from Ewan Henderson to keep the scores level.
And those stops proved pivotal as Wolves loanee Ronan robbed former St Mirren midfielder Jake Doyle-Hayes before rifling an unstoppable strike high into the roof of the net to break the deadlock.
Hibs threw everything they had at the Saints in the closing stages, but Jim Goodwin's side held firm to pick up their fourth win in five games since returning from the winter break.
The victory gives St Mirren's top six hopes a serious boost, with the Paisley club now sitting just a point behind Dundee United in sixth and two behind Hibs in fifth spot.
St Mirren made just one change from their midweek clash with Motherwell, with recent New Zealand cap Alex Greive handed his first start for the club since joining the Buddies.
He took the place of the injured Eamonn Brophy, with Curtis Main and Conor McCarthy back available from their respective knocks with both among the substitutes.
There was an early scare for the Saints when Demetri Mitchell burst down the left wing and cut a low ball into the box that Joe Shaughnessy failed to deal with. Richard Tait eventually cleared the danger.
At the other end, some neat interplay on the left flank saw the ball played through for Jordan Jones who zipped a cross into the box.
Greive was lurking, but the chance went begging as the ball skimmed the top of his head before sailing clear.
Mitchell picked up an early booking after wiping out Greive as the Buddies looked to break from a poor Hibs corner.
The Saints should have made more of a terrible pass from Ryan Porteous, with Connor Ronan's pass easily blocked with the Hibs defence wide open.
The home fans were voicing their frustration early as the Paisley side dominated the opening 20 minutes, with Jones and Greg Kiltie driving the visitors up the park.
Richard Tait tried his luck from distance, with Hibs stopper Kevin Dabrowski just about covering the curling effort as it sailed inches wide of the post, before Jones fired over from the edge of the box as Jim Goodwin's side started the game brightly.
Greive was next to capitalise on some less than confident Hibs defending, racing through before producing a low strike that Dabrowski palmed away to safety.
Hibs almost broke the deadlock when some one-touch passes unlocked the Saints defence to send Chris Meuller through on goal. Only a last-ditch block from Marcus Fraser stopped the striker from putting the Leith side in front.
Tait went into the book for a sliding challenge on former Motherwell teammate Chris Cadden, with the game increasingly feisty as the first half wore on.
St Mirren broke forward yet again with Ronan releasing Jones on the left wing. With Greive and Henderson breaking into the box, the former Killie and Rangers forward could only find Dabrowski's hands with the goal at the Buddies' mercy.
A short corner routine from St Mirren saw Jones tee up Connor Ronan, but the Wolves loanee snapped at the chance with his low strike fizzing well wide.
Former Saints midfielder Jake Doyle-Hayes went into the book for another cynical foul on Greive as the striker looked to burst in behind, before a lovely move saw Ronan beat two Hibs defenders before setting up Jay Henderson.
His close-range effort was beaten away by Dabrowski, with St Mirren feeling aggrieved not to be in front as the referee blew the half-time whistle.
Hibs flew out of the traps in the second half, with Cadden setting up Meuller perfectly on the edge of the box. The American shot well over the bar when he really should have done better.
The hosts were on top and only a sublime stop from Jak Alnwick kept the scores level. Kevin Nisbet waltzed past Fraser in the box before teeing up substitute Ewan Henderson, who thought he'd scored only to see Alnwick deny him superbly from close-range.
Seconds later a low cross flashed across the Saints' six-yard box with no Hibs player close enough to tap home.
The Buddies were undeniably under the cosh and Alnwick had to be at his brilliant best once again to beat away a powerful Henderson effort with one hand to keep his side level.
Goodwin's side managed to gain a foothold in the second half, with Jones picking out Kiltie in the Hibs box with a superb cross. The former Killie midfielder glanced his header past the left post.
That foothold quickly turned into a lead as Ronan capitalised on yet more slack Hibs defending. He picked ex-Buddie Jake Doyle-Hayes' pocket before slamming a rocket past Dabrowski, sparking wild celebrations in the Saints end.
Hibs almost equalised immediately as a low cross eventually found its way to Nisbet in acres of space in the box. His tame finish was tipped just wide by Alnwick to keep the Saints' noses in front.
St Mirren were still looking dangerous on the break, with Jones bursting down the right wing before sending in a superb ball across the box that was begging to be tucked away. Unfortunately for the Saints there were no takers to double the lead, with Greive just unable to reach the cutback.
Hibs threw everything they could at St Mirren in the closing stages, with Maloney throwing on several attacking substitutions to try and turn the tide.
But the Buddies held firm to seal an impressive win in Leith, maintaining their unbeaten run in 2022 ahead of St Johnstone's visit to the SMISA Stadium next Wednesday night.
