Rugby is the most popular code at Dilworth. The school's 1st XV had been among the strongest teams in the Auckland 1B Championship for years, winning 49 out of their 52 games since 2011 and reaching 7 finals since 2000. They were finally crowned 1B Champions in 2012 and won the title again in 2013. In 2015, Dilworth made history by beating Onehunga High School, 12-10, in a 1A Championship promotion match and entered Auckland's top-flight for the first time in 109 years. In their debut 1A season, Dilworth finished 7th out of 12 teams, winning five of their 11 regular season games. In 2016, Dilworth lost much of their starting line-up, however, managed to win three crucial matches against Otahuhu 43-3, Onehunga 19-7 and Kelston Boys' 26-14 to secure an 8th-place finish and survival in the 1A.