The European Commission is fully committed to promoting gender equality in research and innovation. It is a priority for the European Research Area (ERA) and a cross-cutting principle under Horizon Europe. Gender equality plans (GEPs) have been established as the primary instrument for implementing institutional changes in Research Performing Organizations (RPOs) to address structural barriers to gender equality in research and innovation. Within this framework, specific objectives are defined, and thematic areas for intervention are recommended. In this regard, the formulation of a GEP for the Institut de Ciències del Mar (ICM), implied a broader challenge as it had to comply with diverse national regulatory frameworks. Nevertheless, the variety of reference frameworks, instruments and approaches did not condition the aspiration to design a GEP that fully responded to the specific context of the ICM. Thus, the GEP became the roadmap to generating an organisation cultural change that allows the effective integration of gender equality across all its areas and actions. Drawing from ICM’s experiences, we aim to share the path undertaken by ICM and shed light on the multifaceted challenges encountered during the GEP’s design and successful implementation. There is a pressing need to transition from mere adherence to the normative framework to achieving genuine gender equality in practice. Transforming normative principles into practice requires tailored and individualised strategies, feasible objectives with measurable results, appropriate measures to achieve them, and indicators to measure progress. This challenge involves effective institutional changes that remove obstacles to gender equality, both inherent in the research system and stemming from the institutional model of human resources management, funding, decision-making and research programs. The commitment to gender equality must transcend the field of research and research to encompass all staff and institutional practices. Successfully transitioning from theory to practice requires institutional commitment, data-driven decision-making, resource allocation, stakeholder engagement, internal collaboration, responsibility, leadership, and strong gender expertise. This paper stems from the European Horizon Project Leading Towards Sustainable Gender Equality Plans in RPOs (LeTSGEPs).