It's a one-year deal worth $800,000, a source told ESPN.com. McKee was paid $2.7 million in a buyout from the St. Louis Blues.
A 13-year veteran who also played for the Buffalo Sabres, McKee had one goal, seven assists and 44 penalty minutes for the Blues last season as they reached the playoffs for the first time since 2004.
"Jay is a strong defensive defenseman who will bring additional experience to our lineup," Penguins general manager Ray Shero said. "He has great size and is an outstanding shot-blocker, and his veteran presence will help in the continued development of our young defensemen."
Pierre LeBrun covers the NHL for ESPN.com.