A costly handball stung St Mirren for the second game in a row as more Premiership points were spilled at Pittodrie.
The Buddies were holding their own against Aberdeen before Declan Gallagher was given his marching orders after handling in the box, with the Dons netting the opener from the penalty spot - just as Motherwell had six days earlier.
Bojan Miovski blasted the hosts in front, before quickly making it two after pouncing to beat Saints keeper Trevor Carson to a deflected cross at the near post.
Liverpool loanee Leighton Clarkson produced a wonderful third on his debut, firing into the top corner from distance to put former St Mirren boss Jim Goodwin's side in cruise control at the break.
Stephen Robinson's men came out fighting in the second half, with Jonah Ayunga reducing the deficit from the spot after Greg Kiltie was bundled over in the box.
But in the end the Dons hung on to claim their first win of the campaign, with Stephen Robinson's side still waiting for their first point.
Curtis Main and Gallagher both returned to their old stomping ground, while Greg Kiltie returned from suspension just in time to replace Mark O'Hara who missed out after his head knock against Motherwell.
Richard Tait slotted in at left wing-back in place of the injured Scott Tanser, with Main preferred to Alex Greive up front alongside Jonah Ayunga as the Buddies kicked off with a 3-5-2 formation.
The Buddies started brightly, with Main almost picking out a teammate in the box after a nice move sprung by an Ethan Erhahon interception.
The Dons began to press back, with Ylber Ramadani turning past Erhahon before unleashing a powerful strike that rippled the roof of the net with Trevor Carson scrambling on the line.
Gallagher, who had already received a less than warm welcome back from his former fans, picked up the first booking of the afternoon aftering lunging in on Hayden Coulson.
That forced Goodwin into an early change, with new signing Leighton Clarkson making a quicker debut than anticipated after joining from Liverpool on the morning of the match.
Clarkson had the perfect opportunity to announce his arrival just a few minutes after stepping off the bench. As the ball broke to him unmarked on the edge of the box, he could only blaze wastefully wide.
Main almost broke into the box as the Saints fought back. He turned inside one defender but couldn't beat another as the chance went begging.
St Mirren were doing their best to break the deadlock early on. A clever Ryan Strain ball in behind released Main down the right wing, with the striker bursting to the byline before fizzing a pass across goal that Kiltie just couldn't get a toe on at the back post.
Despite their promising start the visitors' task got infinitely harder when Gallagher received his marching orders after just 22 minutes.
Aberdeen initially worked the ball beautifully along the line before teeing up Vicente Besuijen in acres of space.
His curling strike beat Carson but crashed back into the box off the post, with Liam Scales' effort desperately blocked by Gallagher on the ground.
Referee Alan Muir was certain the Scotland international had handled the strike, despite the centre back insisting it hit his chest, with Bojan Miovski emphatically putting away the resulting penalty to open the scoring.
St Mirren reverted to a back four in Gallagher's absence, but it was soon two for the Dons as Jonny Hayes' deflected cross to the front post was pounced on by Miovski.
The confident striker capitalised on Carson's hesitancy to claim the loose ball, giving the Buddies even more of a mountain to climb.
The challenge started to look like mounting Everest when Liverpool loanee Clarkson slammed emphatically into the top left corner from outside the box just before the half-time whistle blew.
The Buddies returned looking to ensure the scoreline didn't become a total embarrassment, with Ryan Flynn replacing Main and the visitors' reverting to a back five once again.
Carson came to the rescue early on in the second half, denying Miovski his hat-trick with a fine low save before Richard Tait cleared the danger.
In a rare foray forward, Kiltie did well in the middle of the park before releasing Keanu Baccus. The Aussie midfielder fired wide of the left post, with keeper Kelle Roos still untroubled in the Dons net to that point.
That was soon to change when Kiltie was clumsily barged over in the box by Hayes. Ayunga held his nerve to drill past Roos, who did get a hand on the strike but not enough to divert it over the bar.
The penalty offered a glimmer of hope to the Buddies, with Carson again the visitors' saviour as he again denied Miovski before pulling off a wonderful one-handed stop to deny Besuijen's fierce effort.
Robinson threw caution to the wind in the last quarter of an hour, with strikers Eamonn Brophy and Alex Greive climbing off the bench to replace Ayunga and Baccus.
Brophy flashed a shot over the bar after being teed up by Joe Shaughnessy as the Saints looked to make it interesting in the closing stages.
But in the end Aberdeen substitute Luis Lopes beat the offside trap before calmly chipping Carson to seal the victory.
