Illingworth scored 6/9 points to finish in a tie for third at the 2009 Commonwealth Chess Championship in Singapore.

Illingworth won the First Saturday GM tournament of September 2011 on tiebreak from Levente Vajda scoring 7/9.

[6] These results earned him the title of International Master,[7] which FIDE awarded him in the congress held during the Olympiad,[8] and established him as one of Australia's strongest chess players.

[9] He has also won the New South Wales State Championship for three consecutive years (2011–13) and tied for first place in the 2011 and 2013 NSW Open.

[16] Illingworth won the 2015 Oceania zonal championship after a playoff match against Brodie McClymont.

[20] Illingworth is a professional chess coach and has worked with several of Australia's most promising junior players.