Former Birmingham City co-owners David Sullivan and David Gold have completed their takeover of West Ham United.
The duo sold their controlling stake in Birmingham to Hong Kong businessman Carson Yeung in October 2009 and had been looking for a route back into Premier League football.
Essex-based businessman Sullivan and long-term partner Gold have been installed as joint chairmen of the struggling club, while former Blues chief executive Karren Brady has been appointed vice-chairman.
Lotus Formula One boss Tony Fernandes ended his interest in the Hammers on Monday evening to pave the way for the experienced pair to take the helm.
West Ham had been owned by investment company CB Holding, who stepped in following the financial problems of Icelandic bank Straumur in June 2009.
"I have been interested in running West Ham United for 20 years and I can't wait to start work," Sullivan told the club's official website.
"I enjoyed running Birmingham City for 16-and-half years but everyone there knew my true love was always West Ham United. It will be an immense privilege to lead this great football club and more importantly its supporters.
"Our first priority has to be securing the Premier League status of West Ham. I believe the players at this club have shown great commitment in trying circumstances and the new board and I will get behind them in every way we can.
"We will also look to bring in new players to supplement the squad where needed once we have met with the manager."
Meanwhile, Sullivan has assured manager Gianfranco Zola that his job is safe despite the Hammers toiling down in 16th place in the Premier League table. They had been in the relegation zone prior to Sunday's goalless draw with Aston Villa.
Sullivan added: "West Ham United need stability after all the recent upheavals. We appointed four managers and parted company with two at Birmingham in 16 years. We believe in our managers and give them the time and support they need."