West Brom manager Tony Mowbray has made Stoke City defender Carl Hoefkens his seventh signing of the summer.
The Belgium international, who has signed a two-year deal with the Baggies, plus a year's option in the club's favour, moves to The Hawthorns for £750,000.
Mowbray told Albion's official website: "Carl really impressed me both times he played against us last season.
"I've also watched him play for his country and I believe he's just the type of footballer who will enhance our style of play.
"He's really pleased to be here and is keen to help the club be successful."
The 28-year-old made 96 appearances for the Potters during his two seasons at the Britannia Stadium.