Czech billionaire Daniel Kretinsky has completed his purchase of a 27 percent stake in West Ham, the Premier League club announced on Wednesday.
West Ham said in a statement "it is intended" that Kretinsky and his colleague Pavel Horsky would become members of the board at the London Stadium alongside joint-chairmen David Sullivan and David Gold and vice-chair Karren Brady.
The London club said the deal would help reduce long-term debt and continue the "positive progress" made in recent years.
"On behalf of the board I am very pleased to welcome Daniel Kretinsky, Pavel Horsky and (investment group) 1890s holdings a.s to West Ham United," said Brady.
"We are always looking to continue to progress and Daniel's involvement brings investment which strengthens the club's position and in turn will assist in the development of the club's key areas of focus.
"David Sullivan and David Gold have always been very open about finding the right investors to join them on the journey as custodians of West Ham United and Daniel's strong business acumen and football experience will be of huge benefit to the club."
Kretinsky, who is co-owner of Czech club Sparta Prague, said he was delighted the process had been successfully concluded.
"I am passionate about football," he said. "I greatly appreciate and respect the exceptional history and tradition of West Ham United as well as its loyal and passionate supporter base and also the highly inspiring role it plays in many social programmes and initiatives.
"The development and growth of the club in recent years has been clear for everyone to see and I am delighted to be part of what I believe is a very exciting future ahead."
David Moyes' team are currently third in the Premier League after their 3-2 win against Liverpool on Sunday.