Global cities, the command and control centres of the integrated world economy, are facing a sustainability paradox of greater global competition and greater environmental pressure. This study explores the policy approaches to the sustainability paradox by integrating environmental sustainability and economic competitiveness into the development strategy for "the global city", based on a case study of Sydney. Dissecting Sustainable Sydney 2030, the strategy to guide the City's development in the early 21st century, reveals the approaches used to achieve the integration. The approaches include green economy, sustainable redevelopment, integrated transport and connectivity, development of attractive public space, urban design for sustainable and good-looking urban form, marketisation of sustainability for a competitive edge, and a relational planning approach. Altogether they target mutually supportive benefits of environmental sustainability and economic competitiveness. The findings point out new directions for the City's strategic development, and suggest a useful reference for counterpart global cities to address the common sustainability paradox.