Professional development programs for teachers in higher education are often characterized by top-down approaches, which fail to make appreciable differences in teaching practices. This study uses a qualitative approach to explore activity-oriented design (AOD) as an instrument for collaborative learning in higher education teacher professional development. We examine Teknosofikum, an ongoing project developed in Denmark along three iterations, involving a total of 64 course participants (42 in the hybrid format; 22 online). The study applies the methodology of design-based research: data was collected via 15 semi-structured group interviews, online forums, and field notes/recordings from online meetings and onsite workshops. Data analysis follows the methodology of grounded theory and evidence is given significance inductively, based on contextual data. Four activities were selected to assess the potential of AOD methods in enhancing teacher collaboration, with different aims: reflection, discussion, theory-practice alignment, and participation. Our analysis revolved around three main categories: trust, deep interaction, and shared beliefs/values. The results show how collaborative group work activities have improved trust and knowledge-sharing among participants and have contributed to creating a safe learning environment. The paper concludes that AOD methods could better assist educational designers in promoting professional development courses that aim at enhancing teacher collaboration in higher education.