Midfielder Youssouf Mulumbu has put pen to paper on a new two-and-a-half-year deal with West Brom.
The improved deal signed on Friday will keep Mulumbu at the Hawthorns until June 2014, with the club holding an additional year's option on the Congo international.
Mulumbu has enjoyed a strong debut season in English football and has quickly become a fans' favourite with a series of battling performances.
Baggies boss Roberto Di Matteo is pleased to have tied up a deal for the player who is just a few days shy of his 24th birthday.
"I'm delighted Youssouf has signed his new contract, which is fully deserved," Di Matteo told the club's official website.
"He's had a very good season so far and is a player who wants to learn.
"He's a big favourite with the fans and I think that is down to the fact they recognise he has a specific role here.
"He does a little bit of the dirty work for the team and is a player who gives us balance. He also chips in with some goals, which aren't expected but are a bonus.
"We're all looking forward to carrying on working with Youssouf for years to come."