While Singapore is often considered an island city in the singular sense, the city-state actually consists of many islands, with the Singapore mainland being by far the largest. While most of these islands traditionally had thriving indigenous communities, all have since been displaced over time as the islands were developed to service Singapore's economic and metabolic needs as a rapidly urbanizing and developing nation. Some of the islands have also undergone considerable transformation (through reclamation) which has had significant impacts on the ecologies of the offshore islands. This simultaneously allowed for the ‘ruralization’ of mainland Singapore to provide more green space for nature conservation, recreation and leisure. This paper will provide a brief history of these transformations, drawing on specific examples which serve to illustrate how Singapore's offshore islands have been redeveloped over time to service the nation-state and in response to the changing needs of the urban core. In doing so, the paper examines how spaces on the urban periphery are deeply bound up with processes of ‘urbanization’, given their important role in processes of urban metabolism. In this way, the paper contributes to recent work in urban political ecology which has sought to trace processes of urbanization beyond the city and render visible the socio-environmental inequalities produced therein.