A collaborative effort by policymakers and researchers designed an experiential learning program to empower preuniversity chemistry teachers to integrate Sustainability and Green Chemistry principles into their curricula using case-based learning (CBL) strategies. Eighteen teachers from 17 schools participated in a workshop and a site visit to Singapore's offshore landfill, Semakau Landfill, connecting real-world sustainability challenges to chemistry education. The workshop fostered active learning, with participants experimenting with CBL, receiving feedback, and codeveloping teaching strategies in a supportive environment. Positive participant feedback underscores CBL's potential to promote Sustainability and Green Chemistry in classrooms. This study highlights experiential learning's role in equipping teachers to address sustainability through chemistry education.