Guerin, who earned $2 million last season, said general manager Ray Shero told him the team will not be re-signing him this fall.
According to the Pittsburgh Post-Gazette, Guerin declined to comment.
"He's obviously disappointed," Shero said, according to the newspaper. "It came down to our club making a decision, whether it was giving younger guys a chance or moving in another direction. There were mixed feelings for us. He was a big part of us winning a Stanley Cup. He's a great guy, has a great family."
The 39-year-old, acquired by the Penguins in 2009 from the New York Islanders at the trade deadline, had four goals and five assists in 11 playoff games last season.
Guerin, who has played 17 seasons in the NHL and won two Stanley Cup rings, is hoping to play one more year.