A one group pretest-posttest design of study was used to investigate the impact of Socio-Scientific Issue (SSI) discussion on college students’ awareness of and self-efficacy toward environmental issues, responsibility for sustainable development, and environment-related activities. Thirty-nine students with different majors from a comprehensive university participated in the semester-long SSI intervention study. The teaching intervention is focused on empowering students to develop reflection and argumentation through watching contextual videos of current environmental issues, justifying personal standing position and achieving group consensus, and evaluating and critiquing peer group’s presentations. After 17 weeks of SSI discussion and argumentation, the quantitative results revealed that students’ awareness of environmental issues, responsibility for sustainable development, self-efficacy for environmental issues, and environment-related activities had been significantly promoted. Additional qualitative findings indicate that the SSI discussion has gained the leverage of changing students’ decision-making and standing position on environmental issues from emphasising economic development to supporting environmental protection and sustainability. Overall, this study provides empirical evidences and original insights about the effect of SSI discussion on environmental education through highlighting the importance of engaging students in practicing reflection and argumentation.