The Baggies look to have finally sovled their left-back problem after signing Arsenal defender Kieran Gibbs in a deal believed to be worth £7m.
Albion were interested in signing the 27-year-old earlier in the summer but were unable to meet the Gunners' initial valuation.
However, after Arsenal lowered their price for Gibbs Albion were unable to strike a deal.
"I'm delighted to welcome Kieran to the Club," said Chairman John Williams.
"We have recruited another quality addition, an England player with bags of experience at Premier League and Champions League level. We are confident he will do well for us."
Gibbs has been at Arsenal since the age of 14 and won the FA Cup three times with his boyhood club.
But he is now ready for a new challenge at The Hawthorns and says he is looking forward to working with Tony Pulis and hopes to improve areas of his game.
"I would like to say how delighted I am to sign for Albion," said Gibbs on Twitter.
"It has been an amazing journey to play for my childhood club. I would like to thank Arsene Wenger for giving me the chance to start my career and fulfil a dream.
"Now it's time for next chaper with West Bromwich Albion and I can't wait to get started with the boys."
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