Dyer completed a move to West Ham on 16 August 2007 for £6 million, signing a four-year deal. He made his debut for West Ham in a 1–0 away win at Birmingham City on 18 August 2007. However, this was one of the few positives in Dyer's time at West Ham as he was thereafter blighted by injury. Just ten days after his debut, he was stretchered off after a tackle by Joe Jacobson in a League Cup match against Bristol Rovers that resulted in his right leg being broken in two places. Dyer subsequently missed the rest of the 2007–08 season. His injury was re-assessed in August 2008, when it was decided that a six-week specialist rehabilitation programme was required before he began pre-season training.