Traditional hierarchical leadership has been implicated in patient safety failings internationally. Given that healthcare is almost wholly delivered by multidisciplinary teams, there have been calls for a more collective and team-based approach to the sharing of leadership and responsibility for patient safety. Although encouraging a collective approach to accountability can improve the provision of high quality and safe care, there is a lack of knowledge of how to train teams to adopt collective leadership. The Collective Leadership for Safety Cultures (Co-Lead) programme is a co-designed intervention for multidisciplinary healthcare teams. It is an open-source resource that offers teams a systematic approach to the development of collective leadership behaviours to promote effective teamworking and enhance patient safety cultures. This paper provides an overview of the co-design, pilot testing, and refining of this novel intervention prior to its implementation and discusses key early findings from the evaluation. The Co-Lead intervention is grounded in the real-world experiences and identified needs and priorities of frontline healthcare staff and management and was co-designed based on the evidence for collective leadership and teamwork in healthcare. It has proven feasible to implement and effective in supporting teams to lead collectively to enhance safety culture. This intervention overview will be of value to healthcare teams and practitioners seeking to promote safety culture and effective teamworking by supporting teams to lead collectively.