In an effort to increase the livability of its cities, public agencies in Australia are investing in green infrastructure to improve public health, reduce heat island effects and transition toward water sensitive urban design. In this paper, we present a simple and replicable approach to building a business case for green infrastructure. This approach requires much less time and resources compared to other methods for estimating the social and economic returns to society from such investments. It is a pragmatic, reasonably comprehensive approach that includes socio-demographic profile of potential users and catchment analysis to assess the economic value of community benefits of the investment. The approach has been applied to a case study area in the City of Brimbank, a western suburb of Greater Melbourne. We find that subject to a set of assumptions, a reasonable business case can be made. We estimate potential public benefits of avoided health costs of about AU$75,049 per annum and potential private benefits of AU$3.9 million. The project area is one of the most poorly serviced areas in the municipality in terms of quality open spaces and the potential beneficiaries are from relatively low income households with less than average health status and education levels. The values of cultural (recreational benefits, avoided health costs, and increased property values) and regulating (reduction in heat island effect and carbon sequestration) ecosystem services were quantified that can potentially offset annual maintenance costs.