Greg Richards has signed with Leigh Centurions until the end of 2018.
The Grand Final winning forward made his debut for the club in 2013 and went on to play 73 times, scoring one try.
He started his amateur career with Barrow Island and was picked up by Saints in 2011 – going on to win the showpiece at Old Trafford three years later.
“It’s always tough when a player who has been through the system at the club leaves for pastures new,” Saints CEO Mike Rush said. “Greg has been here a long time; with me in the Academy and also in the first team set up.
“He has always been the utmost professional and, at just 22, has his best years ahead of him.
“There has been strong competition for places here this season though and therefore, reluctantly, it made sense to allow him to join Leigh.
“We wish him the very best in his future career.”
Greg has been on dual registration with Sheffield this season as well as appearing in the Reserves competition.