A former captain and the Knights longest-serving current player, Mata'utia has been granted a release from the final year of his Newcastle deal to secure his long-term future overseas.

He will link with former Knights interim NRL coach Kristian Woolf, who is head coach at St Helens.

The 24-year-old Mata'utia, who debuted on the wing for Australia not long after making his top grade debut for the Knights when he was 18 back in 2014, played 124 NRL games for the club, scoring 31 tries.

He was the only current survivor of the 2014 season under former coach Wayne Bennett.

He captained the Knights in 2017 during a tough re-building time for the club when they had little success and endured a period that produced three consecutive wooden spoons.

A South Newcastle junior who captained the Australian Schoolboys, Mata'utia was also forced to fight his own injury demons, with a series of concussions at one stage threatening to end his career prematurely.

He was one of four brothers to play for the club and debuted in round 20 in 2014 in the same game as his brother Chanel. Peter and Pat also played for the Knights.

Eldest brother Peter is currently playing in England with Castleford.

"He's been a great servant for the club during some pretty tough times for both himself and the Knights and now he gets the chance to extend his career in England which is a great opportunity for himself and his family," Knights coach Adam O'Brien told the Newcastle Herald.

"He is a great young man and everyone at the club wishes him all the best."