Pulis said last week that he was willing to let fringe players go out on loan and Collins is now well down the pecking order at the Britannia Stadium.
The 31-year-old enjoyed a loan spell at Ipswich earlier this season, making 16 appearances during his time at Portman Road.
West Ham boss Sam Allardyce has been looking strengthen his defence and sees Collins as the ideal man to do it.
Collins will go straight into the West Ham squad for this weekend's home clash with Doncaster Rovers.