This paper uses the notion of material affordances to show that a focus on how people engage with materials helps understanding how organizations transit toward sustainability. Material affordances refer to the enablements and constraints afforded by materials to someone engaging with an environment for a particular purpose. Based on a qualitative study of a company's efforts at becoming circular, we show that material affordances are evolutive as organizational members shift focus from the development of products to the establishment of a circular business model. We also show that affordances are distributed across the company's circular ecosystem. Between what they enable and prevent, they invite humans to a dynamic engagement with materials that decenters human agencies to incorporate material agency in such efforts. A key contribution of the notion of material affordances is to put the relationships of humans and materials at the core of a transition toward circularity and sustainability.