He joined West Ham United in November 2003 for a fee of £500,000. After signing for West Ham, new manager Alan Pardew hoped that the powerful striker could have a similar effect on the Hammers promotion hopes the following season. Harewood was the top scorer for West Ham in 2004–05 with 23 goals in all competitions. He returned to top flight football following West Ham's playoff victory at the end of the 2004–05 season, and the 2005–06 season saw Harewood spearheading Pardew's Premiership attack. He scored 14 league goals, including the first top flight hat-trick of the season in a 4–0 home victory against Aston Villa and also put West Ham in front after just 52 seconds against Manchester United also at Upton Park. Harewood became one of the top scoring strikers of the 2005–2006 season and after scoring the winning goal in the FA Cup semi-final against Middlesbrough, Harewood responded by saying, ""I can't really describe how I felt at the time; you can't put something like that into words, it's a chapter in my career that I have dreamed about doing since I was a little kid. After making the big step-up from Nottingham Forest to West Ham, I knew I had to work hard if I wanted to get to where the top strikers in the country were.""