Prop Adam Walker has joined Wakefield on a two-and-half year deal.
The Scottish international has played nine times for Saints since joining from Hull KR.
“As a result of bringing in Ben Barba, we’ve had to take a look at the make-up of our squad for this season and the next,” Saints’ chief executive Mike Rush said.
He added: “We have, therefore, had to create space in our top 25 squad and have reluctantly agreed for Adam to join Wakefield.
“He has worked hard since he joined the club but with a pack, which includes international forwards, has found gaining first team game time difficult.
“We wish Adam all the best at Wakefield and thank him for his efforts in the Red Vee.”
Adam began his career at Huddersfield in 2010 before moving to Hull KR for the 2013 season.
There he played close to 90 games – and won the club’s Young Player of the Year award.