Sustainability innovation is often not achievable by a single organisation; even if changes in business operations can lead to great advances towards a more sustainable business model (SBM), the effectiveness of these implementations largely depends on the combined actions of the organisation’s network of partners. The aim of this research is to analyse the way that SBMs and partnerships co-evolve to enhance the sustainability of the involved organisations and spread sustainability culture beyond the network. In doing so, this article presents a case study of the company Alisea as a business operating within a circular business model, along with its network of partnerships. The co-evolution of the business model and partnerships is led by enabling factors that characterise the underlying relationships. The role of cross-sector collaborations is demonstrated in terms of boosting the social and environmental dimensions of the circular business model, enhancing social and economic benefits within and outside the partnerships, and spreading sustainability culture in different sectors.