Dean completed his medical this morning and has put pen to paper on a four-year deal worth £7.25 million to his former club Norwich City.
Ashton will be paraded to the Upton Park crowd this evening ahead of the Live Sky Sports game with Fulham.
He told Norwich’s official site, “I have had a great year at Norwich and would like to sincerely thank the fans and everyone I have worked with at Carrow Road. West Ham are a big club, I am ambitious and at the end of the day the chance of a swift step up to the Premiership is too good to turn down.”