The scaling up of renewable gases is now being presented as a critical and effective component of the EU's long-term decarbonization strategy. Yet, the support schemes implemented for biogas and biomethane are far less studied than the ones dedicated to renewable power generation (e.g., solar or wind). This work bridges this gap by reviewing the supporting policies implemented in the EU and conducting a retrospective comparative analysis of the mechanisms implemented in Germany, Denmark, and Italy. The analysis is based on primary data extracted from policy statements that have been harmonized. Results show that incentivizing the supply side lowers the risk associated with early investments and market development. Conversely, they highlight inhomogeneity among countries in accounting for demand and end-use in their policies. Finally, they point at the availability of feedstock and the geographic and economic structure of a country as factors influencing the development of a market for renewable gases. The analysis stresses the value of policy mix in promoting biogas and biomethane in the EU's energy mix, and it hinges on the importance of scrutinizing sectoral massification, novel business models, infrastructure integration, and enhanced financial accessibility to improve their competitiveness and market advancement within the energy landscape.