Illingworth won the First Saturday GM tournament of September 2011 on tiebreak from Levente Vajda scoring 7/9. Thanks to this result he achieved his first norm for the title of Grandmaster. He scored 7/10 for Australia at the 2012 Chess Olympiad in Istanbul. These results earned him the title of International Master, which FIDE awarded him in the congress held during the Olympiad, and established him as one of Australia's strongest chess players.