Anthony Walker has left Saints to join Wakefield in a bid to gain more first team opportunities.
The 23-year-old forward will start his new career at the West Yorkshire club immediately.
Walker has moved for an undisclosed fee.
He made his debut for Saints against Bradford at the start of the season and found favour as one of Nathan Brown’s preferred bench forwards until an ankle injury curtailed his spell in the side.
He later enjoyed a run on dual-registration before winning caps for Wales in the Rugby League 2013 World Cup.
His next season was also curtailed by injury, making just eight appearance during the 2014 campaign.
Saints chief executive Mike Rush said: “It’s always hard when a player who has come through the system here leaves the club.
“Anthony is a hard working player but has found chances limited in a squad that has a number of forwards.
“We wish him all the best at Wakefield and we will be keeping an eye on how he progresses.”
A former swimming champion, Anthony made 17 appearances in the Red Vee.