Purpose: Engaging students in environmental citizenship to promote education for sustainability (EfS) as an explicit goal of academic courses is not common, notwithstanding wide consensus on its importance. Collaborative learning has rarely been investigated using action research methods in the context of environmental citizenship in higher education; the purpose of this study is to fill the gap. Design/methodology/approach: Adopting Bandura's (2012) theory of self-efficacy and collective efficacy, this study explores how collaborative learning, used throughout an action research-based course, encouraged students' efficacy to implement environmental citizenship in their communities. Data were collected through multiple sources: students' written reflections, instructors' reflective journals and continuous discussions, interviews with students and different documents (course syllabi, lesson plans and students' scientific posters). Findings: The findings of this study indicate that the authors succeeded in creating an appropriate social academic setting for the students to become acquainted with each other and to share ideas, successes and challenges in an accepting atmosphere, which proved beneficial to developing their self-confidence to promote EfS in practice. Adopting collaborative learning in the context of environmental citizenship also increased students' self-efficacy and collective efficacy. Self-efficacy was strengthened in the four sources discussed by Bandura (2012): mastery experiences, social modeling, social persuasion and emotional states. Collective efficacy was developed both in the academic and practical domains. Originality/value: The findings of this study suggest that collaborative learning could serve as a powerful way to promote EfS in higher education, especially in teacher education. This contribution was achieved through integrating academic and practical knowledge foundations, which are required to implement environmental citizenship successfully, supporting learners' initial steps towards becoming change agents in the society.