Arbeloa had been out of contract since he was released by Real Madrid at the end of last season.
Ther former Spain international has signed a one-year deal with the Hammers and it is thought that the signing of the defender will allow Michail Antonio to play in a more advanced role.
The 33-year-old played a total of 238 games for Real Madrid and has enjoyed a decorated career, winning two Champions Leagues, one La Liga title, and two Copa del Rey titles among other trophies with Real Madrid.
He has also won the World Cup and two European Championships with his national sides.