They will meet Saturday night in the UFC 154 main event at Bell Centre. Weigh-ins took place at New City Gas nightclub, where more than 2,000 cheering fans were on hand.
St-Pierre, the lineal UFC welterweight champion who has been out of action for nearly 18 months because of a knee injury, tipped the scale at 170 pounds.
"Just to come back, I miss this so much," said St-Pierre, who will carry a pro record of 22-2 into the Octagon.
Condit, the interim titleholder, checked in at 169 pounds.
"I haven't just been waiting to fight George St-Pierre this week," said Condit, who is 28-5. "I've been waiting to fight him my entire career."
All the other fighters slated to appear on the Saturday night card made weight for the event, including Martin Kampmann (171) and Johny Hendricks (171),
who will meet in the co-feature welterweight title eliminator.