Alan Pardew has been appointed as West Brom's new head coach on a two-and-a-half-year contract.
John Carver, assistant to Pardew during his time at Newcastle, will also join the backroom staff at The Hawthorns.
Pardew has been in advanced talks with West Brom about a return to the managerial ranks over the last few days after emerging as the favourite to take over last week.
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"The immediate challenge will be to get the results we need to pull ourselves up the table," Pardew told West Brom's official website.
"But I'm aware that while I'm joining one of the great, traditional clubs of English football, it is one determined to go forward in the Premier League."
Gary Megson had taken over on an interim basis following Tony Pulis' sacking on November 20, but has left the club following Pardew's appointment.
Pardew was the preferred candidate by a 'unanimous decision', according to chairman John Williams, despite having been out of football for almost a year following his sacking at Crystal Palace just before Christmas last year.
West Brom's Chinese owner, Guochuan Lai, was adamant he wanted someone with Premier League experience, while Pardew also has a strong working relationship with the club's technical director, Nick Hammond.
Hammond was director of football at Reading while Pardew was manager.
"Alan brings the experience of more than 300 Premier League games and the kind of dynamic leadership from which our Club can benefit," said Williams.
Megson was in the dugout on Tuesday night when his side threw away a 2-0 lead in a 2-2 draw with Newcastle United.
"Gary leaves with our gratitude for a sterling job completed in difficult circumstances," Williams added.
"We met today when I explained our position which he understood and accepted in the highly professional manner with which he has conducted himself since Tony's departure."
Pardew will take over a side that could be in the bottom three by the time he takes his first game.
West Brom sit 16th but could be overhauled on Wednesday night by Everton, West Ham and Swansea City.