Pacioretty, 23, showed no ill effect this season of the brutal check he suffered late in the 2010-11 season when Boston's Zdeno Chara rode him into the stanchion at Montreal's Bell Centre.
The left wing finished with a team high 65 points, with his 33 goals second only to fellow American Erik Cole.
"Thanks for the support everyone! So happy to be a part of this organization long - term.. .habs," Pacioretty wrote on his Twitter account on Monday night.
Pacioretty was recognized for his perseverance by winning the Bill Masterton Trophy in June. He came back from a concussion and fractured vertebrae resulting from the Chara hit.
The New Canaan, Ct., native was originally selected 22nd overall in the 2007 NHL Entry Draft by the Canadiens.
The last season was his first full campaign with the club. He had recorded 49 points, with 20 goals, in 123 previous regular season games spread over three seasons.
The Habs did not release financial details but multiple reports suggest it will average out to $4.5 million per season. Pacioretty is scheduled to earn $1.625 million in the final year of his current deal in 2012-13.
Montreal struggled badly last season and new general manager Marc Bergevin has worked to secure long-term deals for two linchpins going forward, having locked up star goalie Carey Price earlier in the summer.
Defenceman P.K. Subban remains a restricted free agent.