This paper seeks to advance the understanding of the complementarity between action learning and lean. Today, this is an underexplored research area, despite the high degree of similarities and syngeneic possibilities between these two research streams. The paper describes an action learning intervention at VELUX, a Danish rooftop manufacturer designed to develop its leaders as lean learning facilitators to cope with the increasing velocity of change stemming from growth, sustainability, and digitalisation agendas. The paper locates the complementary between action learning and lean in the extant literature and presents an account of practice from VELUX for extrapolating five promoting factors for developing leaders as lean learning facilitators. The paper concludes that lean complements action learning with a suite of concepts, systems, practices, and methods for institutionalising ongoing action learning and concepts on how to think and act as a leader to foster a lean learning system consisting of empowered and proficient problem-solvers. Furthermore, action learning complements lean with the underlying learning mechanisms of facilitating and sustaining the change towards instituting leaders as lean learning facilitators and adopting a lean learning system.