The 22-year-old has joined the Hammers on a three-year contract from Danish Superliga club FC Midtjylland for an undisclosed fee, believed to be around NZ $8.7 million.
He had a medical on Thursday afternoon and met with manager Avram Grant before heading to the club’s Boleyn Ground home to finalise his dream move later in the evening.
“I am looking forward to getting started,” he told the club’s website. “My dream has been to come and play in the premier league and I am happy that I am a West Ham player.
“It has been a mad couple of weeks and the last couple of days have been pretty hectic, so I am just happy to be here now. I am pretty decent fitness-wise. I had a game last Sunday so I am in pretty good nick.”
Reid was one of the stars of New Zealand’s historic World Cup campaign and scored a dramatic late equaliser against Slovakia to give his country their first ever point at a senior World Cup. He also helped the All Whites to further impressive draws against Italy and Paraguay.
“The World Cup was a life-changing experience and something I will remember forever. I want to bring the positives from that here on the pitch at West Ham,” he says.
“This club has great history and the league is one of the best in the world. I am looking forward to the challenge ahead.”
Reid, who was born in Auckland and moved to Denmark with his mother and Danish stepfather when he was 10, spent five seasons at Midtjylland and made over 80 appearances for the club.
He became a Danish citizen in 2006 and represented Denmark at under-19 and under-21 level.
Under a FIFA rule change, he became eligible for the All Whites because he had not played for Denmark at senior level.
He will join fellow New Zealanders Ryan Nelsen (Blackburn Rovers) and Chris Wood (West Bromwich Albion) in lining up for an English Premier League club this season.