The new deal for Tamas, 27, includes an option to extend the contract by a year in the club's favour. He first joined the club on loan from Auxerre in January and the deal was made permanent this summer.
West Brom head coach Roberto Di Matteo told the club's official website: "I'm delighted Gabi has been offered this new contract. It is richly deserved.
"He was already effectively committed to the club until 2014 but the improved terms are just reward for the progress and contribution he has made here in the past 11 months.
"Gabi is an important figure both on and off the field and has a big role to play in helping the club achieve our goals this season."
Source: PA
