University food environments are typically dominated by unhealthy food choices. The aim was to investigate associations between on-campus food purchasing behaviours and dietary intake in an Australian university student sample. An online cross-sectional survey was conducted in 2017–2018 with students (n = 362, 71.0% female, mean age 27.5 � 10.5 years) from the University of Newcastle, Australia. On-campus food purchasing behaviours (purchasing frequency and weekly expenditure), dietary intake (diet quality and percentage energy/day from energy-dense, nutrient-poor (EDNP) foods) and sociodemographic and student characteristics (e.g., time spent on campus) were measured. Linear regression was used to explore associations between food purchasing behaviours and dietary intake, adjusted for potential confounders. Mean percentage energy/day from EDNP foods was 31.7 � 14.4. Mean diet quality score was 32.6 � 10.2 out of 73. Higher percentage energy/day from EDNP foods was associated with higher weekly expenditure (β = 0.203, p < 0.001) and more frequent purchase (β = 18.041, p < 0.001 for ≥4 times a week vs. never) of food/drinks on campus. Diet quality was not significantly associated with purchase frequency or expenditure (p > 0.05). Findings are supportive of changes being made to university food environments, as a strategy to improve dietary intake among university students.