Energy transition is a core element of the sustainability transition around which the European Union’s post-COVID recovery strategies are built. While these strategies are being designed primarily by EU Member States, the regional level will be critical for their success. Firstly, because regions are key ‘implementers on-the ground’ of European and national policies. Secondly, because the lacespecificities of regions make them ideal ‘laboratories’ for experimenting with the innovations needed for sustainability transitions. This opens an important research question around how regional innovation policy, and more precisely how the regional smart specialisation strategies (S3) that have been developed over recent years, could provide a ‘ready-made’ framework for discovery and experimentation oriented explicitly to energy transitions. This paper explores this question by combining discussion of the concepts of S3 and energy transitions with an exploratory analysis of the S3 experience in the specific case of the Basque region. The paper highlights that moving from a S3 to a Sustainable S3 (or S4) will require enhancing the connectedness of different parts of existing strategies so that energy transition goals are approached in a holistic manner.