The 28-year-old joins on a four-year contract for a fee of around £2.5 million from Aston Villa.
Collins joined the Hammers in 2005 from Cardiff City along with Danny Gabbidon and spent four years at the Boleyn Ground before moving on to the Midlands in September 2009.
In his time with the club he helped us to reach the FA Cup final in 2006 and played his part in ‘the great escape’ of 2007.
Since then, Ginge has made 109 appearances for Villa scoring 6 goals from centre-back in that time.