This study examines the role of active learning in advancing sustainability education for engineers and scientists, with a focus on cultivating systems thinking, interdisciplinary collaboration, and applied problem-solving. Drawing on a case study of two graduate-level courses at King Fahd University of Petroleum and Minerals (KFUPM), this research explores the implementation of flipped instruction, project- and challenge-based learning, and stakeholder roleplay in engaging culturally and linguistically diverse student cohorts. While most students showed significant growth in confidence and academic engagement, a consistent minority remained disengaged. Contributing factors included language barriers, cultural misalignment, and uneven academic preparedness. The findings underscore that active learning is most effective when integrated with inclusive, context-sensitive instructional design. This case offers new insights into the opportunities and challenges of participatory pedagogy in STEM-based sustainability programs and affirms that when thoughtfully adapted, active learning can play a central role in preparing future professionals to navigate complex sustainability challenges.