Biodiversity offsets are part of a new suite of biodiversity conservation instruments designed to mitigate the impacts of economic developments on species, habitats and ecosystems. Led by an international collaboration of representatives from companies, financial institutions, governments and non-governmental organizations (NGOs), the Business and Biodiversity Offsets Programme (BBOP) of the market-oriented Forest Trends group, has created a global framework through which principles and standards for biodiversity offsets are being established. These enable the apparently unavoidable harm caused by development to be exchanged for investment in conservation activities both at different geographical locations and in the future. Offsets can also be traded via bespoke markets for environmental conservation indicators. Given a globalizing 'green economy' discourse that conservation can be a profitable enterprise if guided by market-based mechanisms and the entwining of ecological with economic spheres, biodiversity offsets are becoming key to current entrepreneurial interest in biodiversity conservation. The 'green rush' of my title refers to both this interest in conservation activities that can be marketized, and to an associated appetite in business and financial sectors for incorporating biodiversity offsets as part of a strategy for 'greening' the environmental harm caused by developments. I illustrate the uses to which biodiversity offsets are being put, through a case study connecting the extraction of uranium in Namibia for the generation of nuclear power in the UK. Biodiversity offsets are invoked to satisfy requirements for off-site mitigation of environmental harm at points of both extraction and 'consumption' of uranium in this case. I highlight some of the (anti-)ecological assumptions guiding calculations of complex ecological assemblages so that they can become biodiversity offsets, and draw attention to the intensified distributions of new environmental values with which biodiversity offsets may be associated.