Match ends, Aberdeen 2, St Mirren 0.
Scott Vernon and Barry Robson scored as Aberdeen inflicted a first defeat in seven matches on St Mirren.
St Mirren's centre-backs failed to deal with Jamie Langfield's punt which allowed Vernon in to fire the first past Saints goalkeeper Marian Kello.
The Buddies threatened through a Paul McGowan curled effort after the break.
But Robson sealed the match in spectacular style as his corner swung directly into Kello's net to ensure the Dons stay fourth in the Premiership.
It is also an 11th clean-sheet for Derek McInnes's men, who have now secured three wins on the bounce.
Solid defending was beginning to become commonplace for St Mirren, too, with three clean-sheets in their last four coming into this match.
But it came to an abrupt end at Pittodrie.
Aberdeen were in the ascendancy right from the early stages, Peter Pawlett cutting in from the right and taking a shot on goal which was deflected wide.
Pawlett had scored a beauty for the Dons last weekend and looked bright as part of a front three alongside Vernon and Niall McGinn.
St Mirren did have ball in the back of the net when Steven Thompson turned in at the near post from Jason Naismith's cross, but the linesman flagged for offside.
Vernon, playing instead of Calvin Zola, had missed one chance before he got his sixth goal of the season - assisted by goalkeeper Langfield.
Confusion between Marc McAusland and Darren McGregor following Langfield's launched ball, meaning Vernon could run on into the box to beat Kello.
Another great opportunity fell to the Englishman minutes later, but the Aberdeen front-man fluffed it on this occasion.
After half-time, St Mirren took the game to their hosts and McAusland may have converted if he had been able to connect with a cross.
McGowan then curled one in on goal from 25 yards only to see it comfortably held by Langfield.
Aberdeen's second goal came rather bizarrely but some credit must be given to the whipped delivery of Robson, whose corner kick deceived everyone to fly into the net.
St Mirren protested that Kello had been fouled but those claims were to no avail.
Michael Hector's weak shot and Jonny Hayes' effort could have extended Aberdeen's lead, but just the two goals would have to do for a healthy Pittodrie crowd.
- 8FloodSubstituted forHayesat 54'minutes
- 22JackBooked at 29mins
- 15RobsonSubstituted forLowat 71'minutes
- 16PawlettSubstituted forShaughnessyat 86'minutes
- 7McGinnSubstituted forHarkinsat 73'minutes
- 2van Zanten
- Craig Thomson
- Shots on Target
Second Half ends, Aberdeen 2, St Mirren 0.
Ryan Jack (Aberdeen) wins a free kick in the defensive half.
Foul by Paul McGowan (St Mirren).
Foul by Russell Anderson (Aberdeen).
Steven Thompson (St Mirren) wins a free kick in the defensive half.
Attempt saved. Scott Vernon (Aberdeen) right footed shot from the centre of the box is saved in the centre of the goal.
Attempt saved. Gary Harkins (St Mirren) right footed shot from the centre of the box is saved in the centre of the goal.
Attempt missed. Michael Hector (Aberdeen) right footed shot from the centre of the box misses to the left.
Substitution, Aberdeen. Joe Shaughnessy replaces Peter Pawlett.
Ryan Jack (Aberdeen) wins a free kick in the attacking half.
Foul by Gary Harkins (St Mirren).
Attempt missed. Gary Harkins (St Mirren) right footed shot from the centre of the box is close, but misses to the left.
Foul by Michael Hector (Aberdeen).
Gary Harkins (St Mirren) wins a free kick in the defensive half.
Corner, St Mirren. Conceded by Nicky Low.
Attempt missed. Darren McGregor (St Mirren) header from very close range is too high.
Corner, St Mirren. Conceded by Russell Anderson.
Substitution, St Mirren. Gary Harkins replaces John McGinn.
Mark Reynolds (Aberdeen) wins a free kick in the attacking half.