Harmful fisheries subsidies contribute to overfishing leading to environmental and societal impacts. If only fisheries and ecosystems within the subsidising nations’ jurisdiction were affected, then unilateral actions might be sufficient to help safeguard our ocean and the people reliant upon it. However, just as fish move between jurisdictions, so too do the subsidised fishing fleets that target them. As such, the impacts and solutions to subsidies-induced overfishing are often matters of international concern. Mapping the distribution and flows of harmful subsidies is therefore key to understanding these concerns, informing multilateral reform, and empowering impacted nations to strengthen the terms of access to their waters and resources. Here we quantify the amount of harmful fisheries subsidies that supports fishing in the high seas, domestic and foreign waters. We estimate that between 20% and 37% of all harmful fisheries subsidies support fishing in foreign waters or the high seas, that is outside the jurisdictions of the subsidising nations. We show that harmful subsidies primarily originate from nations with high-Human Development Index (HDI), strong fisheries management capacity and relatively sustainable fish stocks, yet disproportionately impact nations with low or very low-HDI, lower management capacity and more vulnerable fish stocks—40% of the harmful subsidies that support fishing in very low-HDI nations waters originate from high-HDI and very-high HDI nations. We show that Asia, Europe, and North America, are net subsidy sources; they provide more harmful subsidies to their fishing fleets than their respective ecosystems are impacted by; while Africa, South, Central America and Caribbean, and Oceania are net subsidy-sinks. This discrepancy between the source of harmful subsidies and the nations that are ultimately impacted is unsustainable and unjust. Prohibiting all harmful subsidies to distant-water fishing and fishing in the high seas—with narrow exceptions for Small Island Developing States—should be prioritised to support the advancement of sustainable and equitable fisheries worldwide.