Over its 3-year lifetime, the TRANSGEO Project has focused on repurposing abandoned or idle oil and gas wells for geothermal energy production across Central Europe. By recycling these valuable physical assets and giving new employment opportunities to highly skilled hydrocarbon workers, our project uses available resources to find sustainable and economic solutions to one of society’s most pressing problems, the need for energy. Our main objective has been to provide knowledge and information for accelerating the energy transition, by transforming existing fossil fuel infrastructure into renewable heat sources. To achieve this, TRANSGEO has developed Engineering Workflows which give step-by-step information on how to transform old wells into new geothermal heat or electricity sources, carried out socio-economic analyses which put a price on the work required to redevelop a well, and created a database of 9.000+ wells that feeds a publicly-available online Well Assessment Tool which evaluates well availability and suitability for reuse across the 5 partner countries (Austria, Croatia, Germany, Hungary, and Slovenia). In addition, we identified the suitable wells and conducted feasibility studies for 8 selected pilot sites and regions as examples of potential redevelopment projects. Finally, we produced an extensive Transnational Strategy and Action Plan with a hierarchy of actions which are needed to accelerate well reuse and identified the policy makers and other stakeholders who are required to make the changes happen. Altogether, these outputs form a scalable and replicable framework which can be used in Central Europe and beyond to identify, assess, and implement geothermal reuse solutions for the future.