The deal, which kicks in at the start of the 2014-15 season, has an average annual value of $3.85 million, according to the club.
This signing comes two weeks after the Penguins signed franchise center Evgeni Malkin to a long-term deal. The club, however, still faces some major roster decisions, including what to do with defenseman Kris Letang, a Norris Trophy finalist who will be entering the final year of his deal in 2013-14.
Kunitz, 33, has had a successful run playing on a line with with Sidney Crosby since joining the Penguins in 2009. He had a team-high 22 goals in 2012-13, and was second with 52 points. His nine power-play goals also were second on the team, as was his plus-30 rating.