West Ham have completed Dean Ashton's £7.25m transfer from Norwich City.
The 22-year-old passed a medical on Monday and returns to the Premiership after agreeing personal terms with Hammers manager Alan Pardew.
West Ham are to pay £7m, plus a conditional £250,000, while Norwich have negotiated a 15% sell-on clause.
Ashton, a former England Under-21 international, moved to Norwich for £3m from Crewe a year ago and scored 18 goals for the Canaries.
Pardew has admitted his club has paid "over the odds" for the striker, but insisted the opportunity was too good to miss.
"Dean will bring another dimension to our pool of strikers, something I feel we've been missing," he told the Evening Standard.
"It's a show of intent from us. We mean business and hopefully we will end this season in the form we are in now - or even better.
"West Ham are a big club and I am ambitious"
"I'm quite content with that because I feel that in the scheme of things it will prove to be good value."
Crewe will receive £1.5m up front as part of a sell-on clause included in that deal.
Norwich will receive an extra £125,000 if Ashton makes a competitive appearance for the senior England team and an extra £125,000 if West Ham qualify for Europe while Ashton is at the club.
West Ham's managing director Paul Aldridge told his club's website: "We are paying a club record transfer fee for Dean because we feel that, at 22, he represents an investment that can benefit West Ham United for years to come at the highest level."
Ashton, who failed a late fitness test before Norwich's home defeat by Watford on Saturday, said he was looking forward to making a return to the top flight.
He said: "The chance of a swift step up to the Premiership is too good to turn down.
"I'm really delighted to join a massive club like West Ham.
"When West Ham came along I jumped at the chance to be back and playing in the Premiership.
"My ambition has always been to be playing in the Premiership regularly and hopefully the club can make the best of my ability."
"I spoke to Norwich manager Nigel Worthington and the board and told them I wanted to pursue this opportunity. I'd like to thank Norwich for understanding that and allowing myself and my representative to talk to West Ham."
Worthington feels the deal is in the best interest of all parties, adding: "We are always committed to trying to keep our best players at the club.
"But the size of the bid, coupled with Dean's desire to make the move happen, meant that after talking it through with the board and the lad himself, we have decided to accept this offer."