Green signed a four-year deal with West Ham United, where he teamed up with former Norwich striker, Dean Ashton who had been sold to West Ham in January 2006. Green made his debut for West Ham on 19 October 2006 in a 1–0 defeat against Tottenham Hotspur at White Hart Lane. Two of his best performances were when West Ham won 1–0 against Arsenal at the Emirates Stadium and against Manchester United where he helped his team to a 1–0 win, which preserved West Ham's Premier League status. Green kept nine clean sheets in 26 appearances during the league season.