General manager Don Waddell announced the move Tuesday, less than 24 hours after the Canadiens extended their offer to the 21-year-old restricted free agent.
Aho will receive a five-year, front-loaded, bonus-heavy contract worth $42.27 million. It carries an average annual value of $8.454 million.
Waddell - who last week said the Hurricanes would match any offers extended to Aho - called it "an easy decision."
"Sebastian is one of the best players in the league and the centerpiece of what we're building here," Waddell said. "We've spoken to him throughout this process and he's made it clear that he wants to be in Raleigh and be a part of this organization."
Aho had career highs with 30 goals, 53 assists and 83 points last season while helping Carolina reach the Eastern Conference final.
"The Carolina Hurricanes should not be underestimated," Waddell said. "We have a plan and all the resources to win a Stanley Cup."