While at Old Trafford he spent time out on loan at Reading and Burnley before joining West Ham United on a permanent basis in the summer of 2004.

[2] He made his professional debut on 13 October 1999 in the third round of the League Cup as a young United side lost 3–0 at Aston Villa.

[3] After loans at Royal Antwerp in Belgium, he made his Premier League debut on 11 November 2000 in a 2–1 home win over Middlesbrough as an added-time substitute for Dwight Yorke.

[5] He scored two league goals in the title-winning 2000–01 season, one in a 3–0 win at Bradford City on 13 January 2001[6] and the other on 3 March in a 1–1 draw at Leeds United.

[7] After playing rarely for United in 18 months, Chadwick went on a one-month loan to First Division team Reading in February 2003.

[14] On 2 August 2004, Chadwick moved to West Ham United of the newly renamed Championship on a free transfer.

[39] In 2014–15, Chadwick played a part in Cambridge's run in the FA Cup, scoring in their 2–2 home draw with Mansfield Town in the second round.

[40] In the fourth round against his former club Manchester United, he played in a goalless home draw and a 3–0 replay loss on his return to Old Trafford; both sets of fans gave him a standing ovation when he was substituted in the latter game.

[42] After leaving Cambridge United, Chadwick signed for Isthmian League Division One North side Soham Town Rangers in November 2015.

[44] He played the full 90 minutes as England won 5−0 in the 2000 UEFA European Under-21 Championship qualifier at the Madejski Stadium.

[44][45][46] He featured four times during England's qualifying campaign for 2002 UEFA European Under-21 Championship with his last appearance coming in the 5−0 win against Albania on 4 September 2001.

He highlighted how the media had made fun of his appearance, "spots on my face, teeth sticking out, that sort of thing", making particular mention of the abuse he had received on the BBC panel show, They Think It's All Over.