The development of projects for new eco-cities is rapidly becoming a global phenomenon. Alleged eco-cities are being built across a variety of spaces via processes of urbanisation triggering substantial environmental, social and economic impacts. This article investigates how new eco-city projects interpret and practice urban sustainability by focusing on the policy context that underpins their development. The article argues that projects for new eco-cities are shaped in loci by policy agendas tailored around specific economic and political targets. In these terms, the ideas and strategies of urban sustainability adopted by eco-city developers are understood as reflections of broader policy priorities. The case study employed in this article, Masdar City, reveals how the Emirati eco-city initiative is the product of local agendas seeking economic growth via urbanisation to preserve the political institutions of Abu Dhabi. Following the economic imperatives set by the ruling class, the Masdar City project interprets sustainability as ecological modernisation and practices urban environmentalism almost exclusively in economic terms. The article shows how the developers of Masdar City capitalise on sustainability by building an urban platform to develop and commercialise clean-tech products, and concludes that the Emirati alleged eco-city is an example of urban eco-modernisation: a high-tech urban development informed by market analysis rather than ecological studies.