The 23-year-old left wing had a team-high 65 points in 79 games, and he was second in goals with 33 - two fewer than Erik Cole.
The deal, agreed to on Monday, is reportedly worth $27 million with an average of $4.5 million per season. Pacioretty will earn $1.65 next season, in the final year of his current deal, and the new contract will kick in the following season and run through the 2018-19 campaign.
The new contract was finalized two months after he won the Bill Masterton Trophy for perseverance, determination, and dedication to the game. The 6-foot-2 Pacioretty broke his neck and sustained a concussion in March 2011 after taking a hit from Boston's Zdeno Chara, before returning to action last season.
Pacioretty, the No. 22 pick in the 2007 NHL draft, has 53 goals and 61 assists in 202 career games.