Despite the EU’s ambitious goals regarding the expansion of marine renewables as a promising climate mitigation and energy security measure, the majority of hydrocarbon exploitation continues occurring offshore with more than 500 oil and gas installations operating in European seas. Given the grave environmental risks these activities pose, the EU has developed secondary rules with implications for the regulation of offshore energy generation. These normative developments have added an extra layer of regional, supra-national regulation of ocean energy production across European seas, which necessarily interacts with the simultaneously applicable rules under regional sea agreements. The article examines the implications of the normative interplay between EU law and regional sea agreements in terms of shaping the environmental regulation of offshore energy production across Europe. In that respect, it explores whether EU law instruments and the EU’s sophisticated institutional framework can enhance the rules and standards under the regional sea agreements, in terms both of adding normative content to them and supporting their enforcement. In light of the mutual cross-fertilization between the two applicable regimes, the article equally looks into the normative impact of regional sea conventions on the EU legal framework and its implementation in the context of offshore energy production.