In university settings, peer support brings people together based on their student identity. Peer support has been advocated as an innovative intervention to aid student mental health and wellbeing as part of a whole university approach, especially post-pandemic when student support is critical. While the literature describes three types of university peer support for student mental health and wellbeing, peer-led support groups, peer mentoring, and peer learning, the sector lacks agreed definitions for these interventions. Formal reporting on peer support initiatives is rare, suggesting further types of peer support practice may exist. This qualitative study, comprising semi-structured interviews with 16 university staff members at 14 different institutions, aimed to generate comprehensive definitions of the types of peer support used in the sector through template analysis. The study also sought to understand the current practice, experiences, and challenges around implementing peer support interventions for undergraduate and postgraduate students’ mental health and wellbeing from the perspective of the staff who support and coordinate these programmes. Five types of peer support were identified and defined. In addition, the challenges of engagement, resource and capacity, and evaluation were highlighted. Finally, lessons learnt provided potential ways to address the challenges outlined and provided sector guidance for further developing peer support as part of a whole university approach to student mental health and wellbeing.