Slovenia international Robert Koren has agreed a two-year deal at West Brom, with the option of a further 12 months in the club's favour.
Baggies boss Tony Mowbray was delighted with the news,
"Like I said about Robbo yesterday, I want as many good footballers at the club as possible and Robert fits into that category," Mowbray told the club's official website.
"He has become an important member of the squad over the past 19 months and has a terrific attitude.
"I'm delighted he's committed his future to the club."