Semi Ajayi has signed a contract extension which keeps him at The Hawthorns until the summer of 2025.
The Albion defender has made 110 appearances in all competitions since joining from Rotherham United in 2019, scoring nine goals.
Ajayi, who helped the Baggies win promotion to the Premier League in his first season at the club, made 31 Sky Bet Championship appearances during the 2021/22 Sky Bet Championship campaign, while also representing Nigeria at the Africa Cup of Nations in January.
Semi said: “I’m really, really pleased to secure my future here at this football club.
“I’ve thoroughly enjoyed my time here, through the highs and the lows, and I’m excited about the future.
“The talks have been going on for a very long time so I’m glad we’ve finally got it all sorted.
“I can now look forward to next season and doing my best to try and help this club get back to the Premier League.”
Baggies boss Steve Bruce says Semi signing a new deal is a key moment for the football club ahead of the new campaign.
Bruce said: “I’m absolutely delighted Semi has committed his future to us.
“He’s arguably been our best player since I arrived at the club back in February, and I believe he has all the attributes needed to be a Premier League defender.
“This signing is key for us in terms of what we want to do next season and the rebuild which needs to happen. Semi is a crucial player in our team and I’m delighted he’s extended his stay.”