Branislav Ivanovic has sealed a return to the Premier League after signing a one-year contract with West Brom.
The 36-year-old left Chelsea in February 2017 and has spent the last three-and-a-half years in Russia with Zenit Saint Petersburg.
Ivanovic becomes Slaven Bilic's sixth signing of the summer following the arrivals of Grady Diangana, Matheus Pereira, Cedric Kipre, David Button and Callum Robinson.
He told the club's official website: "The Premier League is the best league in the world. I need to challenge myself and I am ready for the challenge. I am really happy to be back playing in the Premier League.
"I hope I am going to be successful here. I have a lot of ambition and I want to prove a lot of things. I will give everything for the team."
Baggies boss Slaven Bilic added: "He's a great addition for us, a team who are newly promoted in the Premier League. He ticks all the boxes for us.
"He's done everything in his career - it's been magnificent. We're delighted. He adds quality and experience on the pitch and off the pitch.
"So it is not only him, it is him plus the influence he will have on not just defenders but the whole team around him. That's why we targeted him as one of our prime targets. It's a great signing for us."
The Serbian defender spent nine years at Chelsea between 2008-2017, winning 10 major trophies which included the 2012 Champions League.
Ivanovic, who can play at right-back or centre-back, was a free agent after leaving Zenit following the conclusion of the Russian Premier League on July 22.
He brings a wealth of Premier League experience to the newly-promoted Baggies, having made 261 league appearances during his time at Stamford Bridge.
'We're doing everything to sign Krovinovic'
Bilic also confirmed on Friday he is trying to sign midfielder Filip Krovinovic on a permanent deal from Benfica, following the 25-year-old's season-long loan spell at The Hawthorns last season.
"As well as new signings we also wanted to keep the loan players from last season, those we wanted to," said the Baggies boss.
"We signed Grady (Diangana) and Callum Robinson and we are doing everything to sign Krovinovic too. That is not easy to do, especially in these circumstances with coronavirus.
"It is not easy to get the players that you want, but we are trying and hopefully we can do it."
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The summer transfer window will run for 10 weeks from July 27 and close at 11pm on October 5.
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