In the era of blue growth, ocean multi-use is gaining popularity for its potential environmental, economic and societal synergies. Expectations are high for multi-use applications to alleviate marine spatial allocation conflicts amongst users of the sea, and to stimulate innovative ways of sustainably exploiting marine resources. However, a potential barrier to implementing multi-use and co-location is the lack of a well-defined framework to evaluate the impacts of ocean multi-use projects. This paper introduces the Ocean Multi-Use Assessment Framework (OMAF), which builds upon traditional environmental impact assessments but expands to include societal and economic dimensions. In addition to these three pillars of sustainable development, the framework incorporates two critical conditions: technological feasibility and regulatory appropriateness (legal, policy, and governance). The framework promotes the use of scenarios to compare single-use and multi-use approaches in an integrated manner. This approach allows for a comprehensive, holistic evaluation of multi-use projects compared to single-use alternatives, supporting decision-making. Strong stakeholder engagement throughout the process is emphasized. The OMAF has been developed and tested under the EU-funded Horizon 2020 UNITED project, where it was applied to five multi-use pilot projects. Despite challenges related to data availability for emerging marine activities, the framework has proven applicable and effective for most projects.