Issue addressed Marketing of products harmful to the health of children has been found to be prolific, and occurs across multiple media platforms and in several settings, including organised sport, thus potentially undermining the health benefits inherent in sports participation. Through website audits, this study investigated the nature and extent of unhealthy food, beverage, alcohol and gambling sponsorship across peak Australian sporting organisations. Methods A structured survey tool identified and assessed sponsoring companies and products displayed on the websites of the 53 national and state/territory sport governing bodies in Australia receiving government funding. Identified products were categorised as healthy or unhealthy, based on criteria developed by health experts. Results There was a total of 413 websites operated by the 53 sports, with 1975 company or product sponsors identified. Overall, 39 sports had at least one unhealthy sponsor, and 10% of all sponsors were rated as unhealthy. Cricket had the highest percent of unhealthy sponsors (27%) and the highest number of unhealthy food and beverage sponsors (n≤19). Rugby Union (n≤16) and Australian Football (n≤4) had the highest numbers of alcohol and gambling sponsors respectively. Conclusions Sponsorship of Australian sport governing bodies by companies promoting unhealthy food and beverage, alcohol and gambling products is prevalent at the state/territory and national level. So what? Regulatory guidelines should be established to limit such sponsorship and ensure that it is not translated into promotions that may reach and influence children.