There is an urgent need to develop climate leaders who can inspire and support mitigation and adaptation actions. This exploratory study assessed the experiences of two student populations: (1) remote learners who participated in, and (2) student co-creators who co-designed, the Massive Open Online Course (MOOC) Act on Climate: Steps to Individual, Community and Political Action (AoC). It examines the extent to which participation and involvement in the course facilitated the development of climate leadership practices of both populations. MOOC remote learners’ answers to discussion prompts (2099 responses from 705 learners) and student co-creators’ interview responses (n = 10, r = 83%) were qualitatively analyzed, informed by Kouzes and Posner’s (2018) five key practices of effective leaders. Findings suggest that remote learners and student co-creators engaged in these key leadership practices to varying degrees. For example, both groups “modeled the way” by taking climate change action consistent with their values and “inspired a shared vision” by conveying desired futures for the planet. Both remote learners and student co-creators attributed these practices to a range of features embedded in the MOOC (e.g., being prompted to research and take mitigation and adaptation actions) and the process of co-creation (e.g., having the agency to creatively and collaboratively produce course content). Given the positive potential for both populations, this paper argues for more research, including experimental studies, to learn how MOOCs and co-creation processes can best be designed to support participants’ climate leadership development.