Sale Sharks have reached an agreement to bring Glasgow Warriors lock Richie Gray to the club in June 2012.
The 22-year-old Scotland international featured in all four of their recent World Cup matches.
Sale director of sport Steve Diamond said: "Richie is only 22 but has the makings of a world-class forward.
"He has been courted by three Premiership clubs and several French clubs, but he has bought into our vision at Sale Sharks."
Gray, who is 6ft 10ins tall, joined Glasgow in August 2008 after impressive performances for the Scotland Under-20 side and signed a new two-year contract in 2009.
"Sale have had a great relationship with Scottish players down the years, from Bryan Redpath and Jason White through to Alasdair Dickinson, Richie Vernon and Fraser McKenzie," said Diamond.
Warriors say that Gray will leave the RaboDirect Pro12 club despite discussions over several months "culminating in an extremely competitive and prompt contract renewal offer" to the forward who has been capped 16 times.
And Gray told Glasgow's website that the decision had been "the hardest call of my career".
"Being a proud Glaswegian, it's been a massive honour to wear the blue and black jersey and I'm looking forward to enjoying more special days in it before my time here ends," he said.
"I was impressed by the efforts that the club and Scottish Rugby made to keep me in Glasgow and it's without doubt the toughest decision I've ever had to make.
"This isn't about money: I've always been keen to test myself in England and I feel this is a good opportunity to do so."
Glasgow chief executive Kenny Baillie expressed his disappointment at Gray's decision.
"A concerted effort to retain his services has been made across many weeks by a significant number of people within Glasgow Warriors and Scottish Rugby," he said.
"The package we presented to him was certainly substantial from both a playing and financial point of view and Richie has informed us that this was an extremely difficult decision to make.
"We'll be sad to see him go, but it's important to emphasise that Glasgow Warriors are far from a one-man team."
Scottish Rugby chief executive Mark Dodson stressed that the governing body would continue its efforts to keep the national team's top players in the country.
"We did everything in our power to hold on to him, but we respect his decision and look forward to supporting him as a key component of the national team," he added.