Transnational environmental law (TEL) is a relatively new term in the environmental law discourse. The scope of TEL encompasses considerably more than either domestic environmental law or international environmental law; it transcends geographical and functional boundaries; and it includes a multifarious range of norms that are created and enforced by multiple state and non-state actors. This chapter seeks to elaborate upon and to unpack the notion of TEL and to understand the steady emergence of TEL as the latest analytical approach focused on those legal norms that govern the human-environment interface in the global sphere. It does so by reflecting on the various considerations that are driving the emergence of TEL including globalisation; the shift of focus from “government to governance”; the issue of fragmentation of international environmental law and governance; and the “radical” idea of the Anthropocene and the increasingly urgent need for enhanced global environmental governance that its imagery calls for. The chapter also reviews the conceptual state of the art by briefly investigating several descriptions of TEL and by identifying and discussing the various processes of transnationalism that are creating TEL. Finally, the chapter applies the TEL framework to the global environmental rights sphere in an attempt to illustrate practically how, and the extent to which, TEL is emerging as a contemporary analytical approach.