Japan international midfielder Junichi Inamoto has agreed to join West Brom on a two-and-a-half year deal.
Inamoto has played in the Premiership for Arsenal and Fulham
Inamoto arrives at the Hawthorns from Japanese side Gamba Osaka, who will get £200,000 upon his first match.
Although currently sidelined with a leg injury, Inamoto is expected to be fit to play again in October.
Baggies boss Gary Megson told the club's website: "I'm delighted to sign Junichi. He is not fit now, but we wanted to do the deal while we could."
Had West Brom waited for Inamoto to complete his recovery from injury, the transfer deadline would have passed.
Instead, the club has negotiated a deal which includes a clause stating if Inamoto fails to reach full fitness and make a senior appearance for the club, no fee will be payable.
Albion would then be free to release the player.