Fossil fuel subsidies, like subsidies to the fishing sector, lead to trade-distorting and ecologically harmful practices. The US$35 billion in subsidies provided by countries every year to the fishing sector leads to more and more boats being built, even as 90% of fish stocks are either fully exploited or overfished. An estimated US$444 billion in subsidies are provided annually for the production of fossil fuels by G20 countries, even as evidence emerges that oil, gas and coal reserves must remain unexploited to limit global warming increases to 2° Celsius. Of course, each country has its own development priorities, livelihood concerns and need for food and energy security. Agreeing upon subsidy reform is a complex undertaking that requires the assessment of social, political and historical considerations, as well as the involvement of international and transnational legal regimes that govern climate change, energy, fisheries and trade. This article reviews proposals for reform within the World Trade Organization and regional trade agreements, including the new disciplines on fisheries subsidies that were endorsed in the text of the Trans-Pacific Partnership. Although the latter agreement is unlikely to enter into force, consensus is emerging on the need to prohibit subsidies that contribute to overfishing or that are linked to illegal, unreported or unregulated fishing. The article shows how these legal developments might inform attempts to limit fossil fuel production and consumption subsidies. It highlights the need for learning and open deliberation about subsidy reform by affected stakeholders, including representatives from international organisations and civil society. It also points to new arrangements that link compliance with subsidy rules to standards and benchmarks from fisheries regimes, and demonstrates how such inter-regime connections are legitimate in the context of the fragmentation of international law. While reform to fisheries subsidies is still preliminary and fraught, there are useful lessons for the equally important project of energy transitions.