West Brom have appointed Sam Allardyce as manager on an 18-month contract.
Allardyce, who has not managed since leaving Everton in 2018, takes over after the club sacked Slaven Bilic.
The former England boss, 66, has previously taken charge of seven clubs in the Premier League and is yet to be relegated from the top flight.
Allardyce joins the Baggies along with long-time assistant Sammy Lee with the club 19th in the table with seven points from 13 matches.
The Dudley-born manager started his coaching career with West Brom under Brian Talbot in 1989 and his first game as boss will be when the Baggies host Aston Villa in a West Midlands derby on Sunday.
The Baggies earned a surprise 1-1 draw at Manchester City on Tuesday but have won only one Premier League match this season, beating bottom club Sheffield United 1-0 on 28 November.
Sporting and technical director Luke Dowling, said: "In Sam we have a man who has a proven Premier League pedigree with a track record of improving every club he has managed.
"We believe and, more importantly Sam believes, we have a group of players that have the quality needed to give the club its best chance of Premier League survival."
Allardyce does have a seven-figure bonus in his contract if he keeps West Brom up.
There is also a break clause in the contract at the end of the season.
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Allardyce was sacked by Everton in May 2018 after six months in charge. The side were 13th in the Premier League when he took over and finished the season in eighth but Allardyce was criticised for the side's style of play during his reign.
Before joining the Toffees, Allardyce had resigned as Crystal Palace manager after five months with the side.
The Palace job was his first since an ill-fated one-game spell as England manager which ended following a Daily Telegraph investigation that claimed he offered advice on how to "get around" rules on player transfers.
The FA said Allardyce's conduct "was inappropriate" and he apologised, adding "entrapment had won".
Allardyce's managerial career has also included spells with Bolton Wanderers, Newcastle, Blackburn, West Ham and Sunderland.
Analysis - West Brom will hope Allardyce has not lost his magic touch
Simon Stone, BBC Sport
The ruthless manner West Brom have acted since Saturday's defeat at Newcastle is underpinned by one thing - Premier League survival.
In 2017, they sacked two managers in a desperate attempt to stay up, which ultimately failed.
Unlike near-neighbours Wolves and Aston Villa, who have received huge investment from their owners, Baggies chief Guochuan Lai does not put money into the club. Ideally he would sell up and move on with a tidy profit.
But for that to happen, West Brom need to stay in the top flight.
When former chief executive Mark Jenkins spoke to BBC Sport in August, he said the club would have needed a cash injection to get it through the current campaign had promotion not been secured.
Those responsible for running the club do not want to find themselves back in the same situation.
So, after losing at Newcastle, it was decided to make a change.
However, rather than leave the club rudderless as it prepared for a game at Manchester City, Bilic remained at the helm until all the issues around bringing in a replacement were resolved.
That Bilic was a dead man walking when he watched his team produce a defiant performance to get a point at Etihad Stadium - and then learned of the rumours he was to be sacked before he had returned to the Midlands - does not look great for West Brom.
But the brutal truth is Bilic will be compensated - and West Brom did not believe he was the right man to drag them out of the mire.
Allardyce, on the other hand, has form for doing exactly that. Most notably he pulled Sunderland away from trouble in 2016 and then, after his traumatic spell with England, did the same with Crystal Palace the following season.
His body of work also includes taking Bolton into Europe, West Ham into the Premier League - and keeping them there - and stabilising Everton by lifting them from 13th to eighth in 2018.
More than two-and-a-half years have passed since Allardyce - a Wolves fan as a boy - took charge of a top-flight match.
West Brom will desperately hope the 66-year-old has not lost his magic touch.
Big Sam to the rescue
This is not the first time Allardyce has been brought in to steady the ship at a struggling club.
He joined Blackburn in December 2008 when Rovers were 19th in the top flight and the side finished the season 15th.
A year later Allardyce guided them to a 10th-place finish before joining West Ham, who had just been relegated from the Premier League.
He oversaw an immediate return via the Championship play-offs, and finishes of 10th, 13th and 12th followed.
Sunderland were 19th in the top flight when Allardyce took charge in October 2015 and eventually secured survival, finishing 17th.
He then took Crystal Palace up to 14th from 17th in his short spell with the Eagles before joining Everton.
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