Avram Grant led Portsmouth to the FA Cup final where they lost 1-0 to Chelsea
West Ham have appointed Avram Grant as the club's new manager on a four-year contract, subject to a work permit.
Grant, 55, succeeds Gianfranco Zola who was sacked after the Hammers finished 17th in last season's Premier League.
The Israeli led Chelsea to the 2008 Champions League final and Portsmouth to this season's FA Cup final.
"I'm proud and honoured to be the manager of West Ham. It's an exciting challenge and I'm ready to do my best," Grant told the Hammers website.
"This is a fantastic club with great fans and a history that is respected around the world. I am looking forward to getting to work with my players in July and preparing for the new season."
Hammers co-chairman David Sullivan added: "I am delighted to welcome Avram to West Ham and am confident he will prove a success.
"We have taken our time over this appointment and are certain we have got the right man."
Grant is likely to bring in his own backroom team, and Zola's assistant Steve Clarke - who worked with Grant at Chelsea - is not expected to have a role at Upton Park.
Grant was sacked by Chelsea shortly after they lost to Manchester United on penalties in the Champions League final in 2008.
He returned to the Premier League with cash-strapped Portsmouth last October, first as director of football, and then as manager after Paul Hart was relieved of his duties at Fratton Park in November.
Pompey went into administration in February and were subsequently relegated to the Championship, while Grant quit as boss on 21 May after the 1-0 FA Cup final defeat by Chelsea - but his success in getting to Wembley won many plaudits.
He won 10, lost 16 and drew seven of his 33 matches in charge of the Hampshire club.
Hammers co-chairman David Gold, speaking on Wednesday before the appointment was confirmed, told BBC Sport: "After an hour, we knew we could work with this manager. We are very optimistic.
"I think it's time for the football club to get some stability with people that have been there, done that and got the T-shirt.
"The bottom line is the relationship between the manager and the chairman is critical. In our case it's two chairmen so it's even more difficult as you need to have a relationship between three people."
West Ham's owners want Grant to improve a squad which finished in 17th position in the Premier League, one place above the relegation zone, with 35 points from 38 matches.
"We can't put our fans through that again. We want to put together a team that was better than last year," said Gold.
"We were very fortunate. Normally 35 points gets you relegated.
"What we need is a manager who has achieved, has experience. We are not in a position where we can take on young, inexperienced managers."
AVRAM GRANT FACTFILE
1986-2002: Managed Hapoel Petah Tikva, Maccabi Tel Aviv, Hapoel Haifa and Maccabi Haifa in Israel
2002-06 Israel national manager
2006 Director of football, Portsmouth
2007-08 Director of football, then manager, Chelsea
2009-10 Director of football, then manager, Portsmouth
Gold said he hoped the appointment, subject to the relative formality of Grant being granted a work permit, would herald a new era for West Ham, which includes a possible move to the new Olympic Stadium in east London after the 2012 Games.
Having finished ninth under Zola in 2008/09 campaign, the Hammers struggled last season with off-pitch turmoil and a prolonged takeover battle.
"We did ask Franco to keep us up and he did that, but I think we need to move on from that. New owners like to choose their own people," said Gold.
"We are over the worst, we've found most of the skeletons in the cupboard and are looking forward to a bright, exciting future.
"There are still many problems and most of all is the debt at the football club. We believe it is a great club and we can turn this round.
"I've been in football for 17 years and I know the critical thing in any football club are the principles and the manager.
"Like all managers, our new manager will bring his own people in, and we are comfortable with that."
Given West Ham's debts, which Gold and Sullivan reported as £110m when they took over in January, Grant is seen as a perfect candidate for operating in the transfer market with a limited budget.
He is unlikely to be handed a huge transfer kitty, but will be eyeing moves both in and out of Upton Park, with the squad due to report back for pre-season training on 5 July.
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