The Gable Endies took a shock lead after only 11 minutes of the game when Martyn Fotheringham steered a Darryn Kelly cross into the net.
The Warriors equalised after 18 minutes when Tommy Sinclair headed home a John-Paul McBride corner. A couple of minutes later they had a chance to make it 2-0, but McBride's penalty kick was saved by Sandy Wood after Wood had upended Colin Cramb.
Although Stenhousemuir had the stronger strike force, it was Montrose who came closest to taking the lead again when Chris Fahey thwarted Hugh Davidson at close range. Just before half- time Paul Murphy had a header cleared off the line.
The second half started brightly for Stenhousemuir, as they moved to a 3-4-3 formation and began to stretch the Montrose defence. But they were almost caught out on the counter attack that saw Gary Middleton blast over from close range after 55 minutes.
Shortly after this Stenhousemuir were awarded their second penalty after Stuart Ferguson tripped McBride and Cramb converted the penalty.
Three minutes later Sinclair blasted his second after good work by David Templeton and Cramb. This took any pressure off the home side, and further goals followed from substitutes Iain Diack, who thundered a Cramb cross into the net, and Paul McGrillen, who chipped the advancing Wood after being picked out by a Joe McAlpine through ball.
In the last five minutes of the game Montrose had a couple of excellent chances for a consolation goal, but it was not to be their day as Stenhousemur ran out deserved winners.