Cullen said his decision wasn't easy, and credited Penguins general manager Jim Rutherford for allowing him to continue his career, which will enter its 20th season.
"If [Rutherford] hadn't made that phone call a couple of years ago, I'd be coaching youth hockey, so I owe him a lot," Cullen said. "I never would have imagined that [I'd be playing this long in my career]. I've been really blessed, and I am thankful.
"There's a lot of things that have to go right along the way. It's an honor to be able to play in the League this long, and I don't take it for granted. I'm really, really happy to have one more chance this year."
Cullen, who will turn 41 on Nov. 2, is the oldest player currently on an NHL roster. Forwards Jaromir Jagr (45) and Shane Doan (turns 41 on Oct. 10), the only players on NHL rosters last season who are older than Cullen, remain unsigned.
Cullen said he doesn't expect to have a decision made on retirement until after this season, but "I fully expect this to be the last one."
Selected in the second round (No. 35) of the 1996 NHL Draft by the Mighty Ducks of Anaheim (now Anaheim Ducks), Cullen has 689 points (248 goals, 441 assists) with the Penguins, Ducks, Hurricanes, Wild, Florida Panthers, New York Rangers, Ottawa Senators and Nashville Predators in 19 seasons (1,366 games). He has 56 points (18 goals, 38 assists) in 123 playoff games.