The Premier League has confirmed that Blackburn Rovers defender Lars Jacobsen has been permitted to join West Ham on a free transfer.
Negotiations to take Jacobsen to Upton Park continued late into Tuesday and were completed just before the 1800 BST deadline.
The Premier League was forced to delay confirming the transfer as it assessed whether the necessary paperwork had been filed in time.
Now that the league has given the green light to the transfer, Jacobsen has joined the Hammers on a free transfer and has signed a one-year deal.
Jacobsen, 30, joined Rovers from Everton in the summer of 2009 and made 13 Premier League appearances last season. He appeared in all three of Denmark's World Cup games in South Africa.
West Ham have also announced the signing of goalkeeper Ruud Boffin from Maastricht. The 22-year-old signs on a two-year deal.
"We have combined youth with experience this window and are pleased with the work we have done, even in these challenging times for the club," co-owner David Sullivan told the club's official website. "We were determined to keep Scott Parker, as well as Avram's other key players, and were able to deliver on what we promised.
"Half of our eight signings are 23 or under and we are confident they can become major players for the club, while the other four have a wealth of international experience. Thomas Hitzlsperger had a particularly impressive pre-season and we look forward to seeing him play a major role once he returns to fitness."