In the transition towards a circular economy, purchasers play a critical role as gatekeepers to the reuse of circular products in organizational processes. However, there is a need for research on the individual-level determinants of circular purchasing. Integrating the Theory of Planned Behavior, and the literature on organizational citizenship behavior towards the environment and intrapreneurship, we propose that the intention to act pro-environmentally, as expressed by organizational citizenship behavior towards the environment, is critical to circular purchasing. Moreover, we argue that intrapreneurship mediates this association, as intrapreneurs proactively make the effort and take risks in the process of creating new business opportunities. Using a survey among 124 Dutch and Belgian purchasers, this study shows that organizational citizenship behavior towards the environment is positively related to intrapreneurship. Contrary to what we hypothesized, intrapreneurship does not mediate the association between organizational citizenship behavior towards the environment and circular purchasing. Furthermore, purchasers in high-level hierarchical positions showed a stronger positive relationship between organizational citizenship behavior towards the environment and circular purchasing compared to purchasers in low-level hierarchical positions.