Saints held the upper hand against Hearts last season, with the Edinburgh side taking just two points from their three league meetings. But they seem to have put that jinx behind them after taking an impressive victory away from home.
The visitors started the match with Anthony Basso in goal after first-choice keeper Steve Banks was hit by food poisoning, but St Mirren failed to trouble the second-string man with their early efforts.
As they struggled to break down a resolute Hearts back four their best chances came from long-range efforts.
Stephen O'Donnell blasted his attempt from 25 yards high over the crossbar and Ryan McCay was also off target with his shot from 30 yards out.
The Buddies felt they had been hard done by when they were denied a penalty by referee John Underhill midway through the half, as O'Donnell went down in the box.
And it was Hearts who took the lead from a set-piece. Michael Stewart floated a corner into the area and found Andrew Driver unmarked at the far post. He smashed the ball past Chris Smith into the corner of the net with ten minutes of the first half remaining.
St Mirren were forced into a substitution early in the second half after an injury to Will Haining, but the introduction of Stewart Kean up front looked to have given Gus MacPherson's side some extra impetus.
On-loan Chris Birchall had a powerful header controversially turned behind by Jose Goncalves. St Mirren claimed handball but their penalty claims were again turned down by referee Underhill.
The match threatened to boil over just seconds later as Hearts were awarded a penalty at the other end. Stewart went down under the challenge of David van Zanten and the referee immediately pointed to the spot.
Stewart stepped up to take the spot-kick himself and fired his right-footed effort straight past Smith to double his side's lead.
Things finally started to go St Mirren's way ten minutes from time as substitute Mark Corcoran got on the end of an excellent delivery from Birchall and beat a nervous-looking Basso.
But the Buddies' recovery was short-lived, as Andrius Velicka put the match out of reach with an excellent finish less than 60 seconds after coming off the bench.