Strategic Environmental Assessment (SEA) is often accepted as a mean for the transition towards sustainability through decision-making, but it is widely acknowledged that are challenges to overcome. SEA is context-specific, depending on different aspects, including the territorial context. It was identified a lack of research focusing on systematised and consistent studies enhancing SEA context specificity for sustainability in particular territories, namely through tailored practices and procedures. Hence, the main goal was to explore SEA for sustainability in territories with unique features, such as small islands. These territories provide an opportunity to explore and advance SEA for sustainability because small islands have a pressing need for the enhancement of sustainability. To address the research goal an exploratory and inductive mixed-method approach was used, unfolded through (i) a literature review, identifying the main trending topics on sustainability and SEA practices in small islands, (ii) a case-study, using the Azores (Portugal) and Orkney (Scotland) archipelagos, to assess and compare small islands SEA practices with the mainland, (iii) a questionnaire survey, to identify key issues to take into account while preparing SEA for sustainability integration in these territories, and (iv) a conceptual framework, developing the findings of the empirical research phases with further literature review. The operationalization of the framework was conceptualized for the Azores and Orkney archipelagos. The key findings suggest that it could be easier for Azores to operationalize SEA for sustainability while it is expected that Orkney may need creative solutions to overcome different challenges. Transitioning towards sustainability in small islands through SEA needs a strong support from decision-makers and ownership by practitioners and intermediate decision-makers, with an effective involvement of small islands stakeholders (e.g., small islands civil organizations, small islands experts). Islands’ knowledge and cooperation networks need to be established, and a continuous learning process needs to take place