Hargreaves has made 25 Super League appearances this season
Bradford Bulls have signed prop forward Bryn Hargreaves from Super League rivals St Helens on a two-year deal starting next year.
The 24-year-old, who started his career at Wigan, has made more than 100 appearances for Saints following his 2007 switch.
He said: "It's time for a change and for a new challenge.
"I've enjoyed quite a bit of success at St Helens and now I'm hopeful of doing the same at Bradford."
Bradford stand 10th in Super League, having experienced a nightmare run of 12 straight defeats following the announcement in April of coach Steve McNamara's departure to take the England job.
McNamara eventually left in mid-July, since when Lee St Hilaire has been picking the team until the arrival of Mick Potter for next season.
"When I spoke to Lee St Hilaire about joining Bradford I was impressed with what I heard," said Hargreaves, who will follow Potter to Odsal from Knowsley Road. "And I really think the club's going places.
"Their current position is not reflective of where they are right now and I think they will soon be back where they belong."
Bulls chairman Peter Hood said: "Bryn will be a tremendous addition to our squad next season.
"He is still very young and his best years are very much ahead of him but he has a wealth of experience through being virtually ever present in a very good St Helens side for the past two years.
"We are delighted he has chosen to come to the Bulls and he will complement our other prop forwards immensely."