Cronulla co-captain Paul Gallen will play on in what will be his 19th season for the club in 2019.
Gallen, the former NSW captain who played 24 State of Origin matches for the Blues and 32 games for Australia, has decided against hanging up the boots despite turning 37 earlier this week.
The star lock made his NRL debut in June 2001.
Gallen has played 321 matches for the Sharks, including leading the club to its only premiership win in 2016, is closing in on breaking Andrew Ettingshausen's club record of 328 appearances in the black, white and blue.
"I was hoping to get this message to you first and to do that before making this announcement later tonight on The Footy Show but secrets are hard to keep from the media these days. I said earlier in the week that I was close to making a decision on my playing future and after discussions with the Club and with our coach Shane Flanagan I have made the call.
"While we still have some big games to go in 2018 and finishing this season on a positive note is our main focus, hopefully with another Grand Final appearance, I can now confirm that I will be playing on in 2019.
Sharks v Cowboys - Round 23
"Plenty of people quote my age and the fact that I was 37 earlier in the week, however the body feels good, training is still something I look forward to and the feedback from the coach and those that matter, say my contribution to the team on game day is strong.
"I've always said age and my birth certificate would never make this decision for me if everything I've explained above was in order.
"And personally, I believe I've got plenty left to give, which has ultimately led me to make this decision.
If I play 15 games or 25 games next year, while winning is the main aim, part of my role will also be to bring through and to help develop the next crop of talented young players at our Club, as I've tried to do in recent years and as I'll continue to do.
"As for the terms and the contract, I'll sit down with the Club at the end of the year and sort out the details, but at this stage we're concentrating on the Cowboys first, then the big games we have coming up after that.
"I can say that 2019 will be my last season, I now have an end date and with the talent we have here at the Sharks I am confident this year and next can be successful for myself and the Cronulla Club."