Youssouf Mulumbu has signed a new two-and-a-half-year contract with West Brom.
The deal gives the 24-year-old midfielder improved terms as reward for his impressive performances this season, and also includes a club option for a further year, effectively committing him to the Baggies until 2014.
It is the second time in the last seven months that West Brom have given Mulumbu a new deal, showing the impact he has made at the club.
"I'm delighted that Youssouf has signed his new contract, which is fully deserved," said manager Roberto Di Matteo on the club's website.
"He's had a very good season so far and is a player who wants to learn."
Mulumbu has made 19 appearances for West Brom this season, scoring three goals.
"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," Di Matteo added.
"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 all look forward to carrying on working with Youssouf for years to come."