New South Wales prop Daniel Saifiti has extended his contract with the Newcastle Knights for a further two seasons.

Saifiti, 23, will remain at the club until at least the end of 2022.

The front-rower made 21 appearances as the Knights finished 11th this season and becomes the first player to agree to an extension under new coach Adam O'Brien.

"While there have been some tough times, we showed improvement this season and are getting better," said Saifiti, who earned a State of Origin debut in June.

"We've signed some quality players in recent times and that has certainly helped with my development.

"I owe a lot to this club. My brother Jacob and I came here as teenagers to play under-20s and I've been living my dream ever since."