The on loan Rangers player took the plaudits but credit must also go to goalkeeper Pavol Penksa for keeping a clean sheet just six hours after signing.
Penksa’s arrival averted another crisis in goal just a week after the Kirkcaldy club were forced to field forward Ryan Stevenson between the sticks in a narrow defeat by Ayr United.
And the 31-year-old Slovakian’s solid performance was all the more remarkable, given his distressing journey to the UK.
He had been due to arrive on Sunday but his trip was postponed 24 hours after having his passport stolen at Bratislava airport.
Hardie, pictured right, was the hero for the hosts, scoring twice within ten minutes of climbing off the bench. His second came gift wrapped courtesy of Billy O’Brien after the Saints goalkeeper made a costly error.
Raith started on the front foot against the in-form Saints. The match was barely a minute old when Chris Johnston got a break of the ball in a central position outside the area but the diminutive playmaker’s low drive was well held by visiting goalkeeper O’Brien.
Mark Stewart then dragged a left-footed effort wide before having to limp off injured in the 20th minute.
St Mirren were tidy in patches but lacked cohesion in the final third. Their best chance of the first half came when Lewis Morgan had a goal-bound shot cleared by Iain Davidson after the Buddies worked a short corner.
St Mirren were then relieved in first half injury time when Declan McManus’ free-kick hit the outside of the post.
Penksa was called upon after the break to get down to Cammy Smith’s low shot before using his 6ft 4in frame to scramble across his goal and turn Stevie Mallan’s free-kick behind for a corner.
Hardie then scored his first in the 74th minute when he diverted Bobby Barr’s cross into the net before dispossessing O’Brien five minutes later to find the unguarded net.
The victory moves Rovers nine points clear of the Buddies, while Jack Ross’s side remain five points behind Ayr United at the bottom.