Improving population diets is a public health priority, and calls have been made for corporations such as supermarkets to contribute. Supermarkets hold a powerful position within the food system, and one source of power is supermarket own brand foods (SOBFs). Many of the world's largest supermarkets have corporate social responsibility (CSR) policies that can impact public health, but little is known about their quality or practical application. This study examines the nature and quality of Australian supermarkets' CSR policies that can impact public health nutrition, and provides evidence of practical applications for SOBFs. A content analysis of CSR policies was conducted. Evidence of supermarkets putting CSR policies into practice was derived from observational audits of 3940 SOBFs in three large exemplar supermarkets (Coles, Woolworths, IGA) in Perth, Western Australia (WA). All supermarkets had some CSR policies that could impact public health nutrition; however, over half related to sustainability, and many lacked specificity. All supermarkets sold some nutritious SOBFs, using marketing techniques that made them visible. Findings suggest Australian supermarket CSR policies are not likely to adequately contribute to improving population diets or sustainability of food systems. Setting robust and meaningful targets, and improving transparency and specificity of CSR policies, would improve the nature and quality of supermarket CSR policies and increase the likelihood of a public health benefit.