Cullen, 41, has played on one-year contracts for each of the past three seasons, helping the Penguins win back-to-back Stanley Cup titles in 2016 and 2017 before spending the past season with the Wild.
Each of the previous two offseasons, Cullen considered retiring before coming back for another season.
Cullen has played in 1,445 career NHL games, posting 259 goals and 452 assists. He also won a Stanley Cup in 2006 with the Hurricanes.
The Penguins also officially announced their five-year deal with defenseman Jack Johnson on Sunday.