The 35-year-old will extend his career with the Cronulla Sharks into an 18th season after agreeing to a one-year extension.
Gallen, who has played 277 first-grade games, said he always intended to stay with the club he debuted with in 2001.
“I’m definitely pleased. There was never really any doubt it was going to happen,” Gallen told the club’s website.
“I wasn’t really focused on chasing it up, we’re more focused on playing the games at the moment and getting wins. Obviously the past couple of weeks I’ve had a bit of a sore back so been concentrating on that.
“There was never any doubt I was going to play here next year and really excited for what will probably be my last year, you never say never in this game, you don’t know what’s going to happen.
“But I’m certainly excited to be here for another year.”
The Sharks are into a preliminary final and face the North Queensland Cowboys on Friday.