This study examines students’ engagement in online synchronous collaborative learning (OSCL) sessions in a massive open online course (MOOC). The study focuses on the role of digital technologies in facilitating students’ agency in collaborative meaning-making activities. The primary data sources for the study were video recordings of OSCL sessions, which were analysed using the method of interaction analysis and interpreted through the lens of cultural-historical theory. The findings revealed four interconnected activities of collaborative meaning-making: establishing social connections and presence, reflecting on prior learning, sharing digital artefacts and reflecting on shared understanding. The progression from one activity to another unfolded as students contributed to collaborative learning activities using their own ideas and problem-solving approaches. The use of individually created digital artefacts, such as examination assignment drafts, deepened interactions and meaning-making processes, enhancing students’ agency in collaborative learning. The findings of this study provide insights into pedagogical strategies that can enhance student agency in MOOC environments, highlighting the crucial role of digital artefacts in developing students’ agency in collaborative learning.