In today's world, where sustainable development has gained global precedence, cultivating environmental awareness among younger generations has become a central objective of education. This study seeks to develop instructional posters enriched with science cartoons to enhance middle school students' understanding of environmental sustainability. A design and development research approach was adopted to create instructional materials that are both visually engaging and pedagogically sound. Posters were produced on core environmental issues, including renewable energy sources, global warming, pollution of air, water and soil, acid rain, deforestation, desertification and waste management, and each poster was complemented by scientifically accurate and thought provoking cartoons. Expert feedback was incorporated throughout the development process to strengthen the materials' educational value and visual appeal. The resulting posters are posited to be pedagogically effective tools that capture students' attention, concretize abstract environmental concepts and promote long term learning. Consequently, these visual materials are expected to serve as functional educational resources for instilling values such as environmental responsibility, sustainability consciousness and ecological awareness.