A goal either side of half-time saw St Mirren secure their place in the third round of the Co-operative Insurance Cup as Ayr United were beaten at home.
Michael Higdon headed his first goal for the Buddies in the 25th minute from David Barron's cross.
Dean Keenan was sent off for Ayr as the game entered its final stages following a challenge on Billy Mehmet.
And within seconds, Mehmet converted Stephen O'Donnell's cross to seal the Scottish Premier League side's win.
St Mirren were in the ascendancy early on with Ayr goalkeeper blocking a 30-yard free-kick by Mehmet and Stephen McGinn also coming close from range.
At the other end, Mark Roberts' glancing header from Chris Aitken's corner was saved by Paul Gallacher.
Samson then saved a shot by Tom Brighton, who was back in the St Mirren starting line-up for the first time in over a year.
Saints took the lead when Barron collected a throw-in and delivered to the penalty spot, where Higdon glanced into the corner of the net.
The hosts tried to force a leveller before the break but Ryan Stevenson was crowded out in the box as he tried to turn Aitken's corner towards goal.
Mehmet had another free-kick blocked before he set up Andy Dorman to drag a shot wide.
Steven Thomson struck the crossbar with a 20-yard shot in the 70th minute as Ayr continued to struggle with the St Mirren attack.
Samson was then required to save another effort from Higdon.
Ayr had a number of set-piece opportunities to put St Mirren under pressure but could not carve out any meaningful efforts at goal.
And Keenan's dismissal for a professional foul on Mehmet all but extinguished the First Division side's chances of getting back into the match.
Mehmet made sure of St Mirren's progress when he slotted a low drive past Samson from 10 yards in the 90th minute.
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