The veteran was traded to the Avalanche from the Montreal Canadiens in March and played his way into a significant raise after a terrific second half to the season and memorable contributions in the postseason.
Lehkonen, 27, is a strong middle-six presence who makes teammates better, and he really came alive for Colorado during its Stanley Cup run.
"Artturi was a great fit to our team last season and obviously played an essential role in our championship run," general manager Chris MacFarland said. "He is incredibly versatile, can play anywhere up and down the lineup. He has a non-stop motor and never takes a shift off. He's really smart, highly competitive, knows his role no matter what is asked of him.
"Getting length and term for a player of his quality was a top offseason priority and we're thrilled to have him for the next five years."
Lehkonen finished with eight goals and 14 points in 20 playoff games, and scored key markers too, including the game winner in Game 4 of the Western Conference final vs. the Edmonton Oilers, as the Avalanche punched their ticket into the Stanley Cup Final against the Tampa Bay Lightning.
The Avalanche, rumored to be interested in star forward Claude Giroux during the regular season, made the move to acquire Lehkonen to fill a similar role after Giroux was traded from the Philadelphia Flyers to the Florida Panthers. Giroux signed with the Ottawa Senators in free agency on Wednesday.