His twin brother Dean is also a footballer turned football manager, now managing Aldershot Town. On 18 September 2010, they became the first twins to manage against each other in the top five divisions of English football, when Dean was manager of Newport County.
He played as a centre half for Watford, Sheffield United, Birmingham City, Walsall, Bolton Wanderers, Scarborough and Gretna, and was capped once for England at Under-21 level. Whilst at Bolton he played one game alongside his brother.
After retiring from playing he became reserve team manager at Gretna, where he was appointed director of youth development in May 2006,
but was sacked in a cost-cutting exercise a few months later. On 20 May 2008, Holdsworth was appointed to his first managerial role, taking over at Northern Premier League Premier Division side Ilkeston Town from Nigel Jemson, the first appointment of new owner Check Whyte.
On 29 December 2008 Holdsworth was appointed as the new manager of Conference National club Mansfield Town having led Ilkeston to sixth in the Northern Premier League Premier Division, ten points off first placed Hednesford Town with two games in hand.
Holdsworth's house was featured on an episode of Through the Keyhole.
On 18 November 2010, it was announced that Holdsworth had agreed to leave Field Mill by mutual consent less than two years with the club.