Environmental governance in Northern Ireland has been highly problematic and the subject of intense criticism. Since the collapse of the devolved government in January 2017, environmental policy development and urgently needed processes of environmental governance reform have stagnated. Combined with the continuing uncertainty surrounding Brexit, this situation has the potential to exacerbate an already challenging governance context and the severe environmental consequences of political inaction are already becoming clear. This article will reflect on how future environmental governance arrangements in Northern Ireland might develop in light of both distinctive local challenges and reforms that have been proposed for other parts of the UK post-Brexit. Its central theme is the potential for the distinctive environmental governance vulnerabilities present in Northern Ireland to be compounded by Brexit. It concludes that a process of reform centred on the development of common frameworks, underpinned by environmental objectives, principles, rights and duties and enforced via meaningful accountability mechanisms would help strengthen environmental protection even where the political will or power is lacking. Such a process of reform could help address both existing environmental problems and potential environmental governance gaps posed by Brexit, as well as providing valuable lessons for other jurisdictions facing major environmental governance reform or contending with the practical implications of governance without a functioning government.