The deal with the No. 2 pick in the 2019 draft carries an annual salary cap hit of $2.1 million. General manager Chris Drury announced the agreement Thursday.
Kakko, 21, played in 43 games last season, recording seven goals and 11 assists with a plus-nine rating. He also had two goals and three assists in 19 games during the Rangers' unexpected run to the Eastern Conference finals.
Kakko has skated in 157 career NHL games, putting up 26 goals and 32 assists. His best season was his rookie year in 2019-20, when he had 10 goals and 13 assists in 66 games.