Playing mainly as a left-arm spinner, Illingworth made his first-class debut in 1982, promoted to the Worcestershire first team after just two Second XI appearances and taking 3–61 against Somerset.

He played a crucial part in the match, allowing the tourists just 20 runs from his ten overs for the wicket of Jeff Dujon, and then putting on an unbroken partnership of 23 with Mike Atherton as England recorded a thrilling one-wicket victory.

During the 1992 World Cup, Illingworth played in the final, giving away 50 runs in his 10 overs for the wicket of Javed Miandad, and also catching Imran Khan at long-on.

Although his performances in the other two Texaco Trophy matches of 1991 were less impressive, he did take the wickets of Richie Richardson and a young Brian Lara in the seven-wicket win at Lord's, and also held a catch off Phil DeFreitas to remove captain Viv Richards.

[2] He also bowled Richards on his way to 3–110, but two stubborn rearguard displays with the bat (adding 42 with Robin Smith in the first innings and 38 with DeFreitas in the second) could not prevent England sliding to a nine-wicket loss.

Illingworth retained his place for the Fourth Test at Edgbaston, batting at number 11; this match was notable for the fact that all eleven England players had a first-class century to their name.

By 1995, Illingworth had been out of the England side for two years, but the selectors were impressed by his reliable performances for his county, and called him up for the Test series against West Indies.

He also appeared four times in the 1996 World Cup, but thereafter the selectors' preference turned decisively to Tufnell, and Illingworth never played international cricket again.

[4] As at the end of the 2008 English cricket season Illingworth had umpired 47 first-class matches,[5] it was confirmed that he, and Richard Kettleborough, were promoted onto the ICC International list on 9 November 2009.