Industrial symbiosis (IS) provides a strategy for more resource-efficient economies, potentially contributing to several SDGs. However, many potentials remain unrealised as realisation is given low priority in companies. This paper explores the role of companies that incorporate IS in their core business strategy, termed regenerative businesses (RBs). Five cases were followed for four years using a contextualistic approach. Results suggest that RBs are crucial in IS realisations that go beyond low-hanging fruit, as they engage in 'pre-realisation development', motivate others, work persistently to overcome barriers, and, in some cases, mobilise support from public champions. The paper also proposes that RBs not only engage in local realisations but can diffuse and scale up solutions. As RBs are found to be dependent on contextual conditions and, in some cases, collaboration with public actors, support for RBs can be a strategy for the promotion of IS.