Edited proceedings of the 12th International Conference on Decision Support System Technology (ICDSST 2026), held in Plymouth, UK, May 27-29, 2026. The volume gathers the peer-reviewed full papers presented at the conference under the theme ‘Decision Support System Technology for Sustainable and Resilient Transitions’, covering decision support methodologies, group decision and negotiation, analytics and artificial intelligence for decision making, and applications supporting sustainable and resilient societal transitions.