Nonprofit organizations (NPOs) have deployed various strategies in motivating businesses to source sustainably, such as the co-development and promotion of sustainability certification and direct collaboration in cross-sector partnerships (CSPs). This is an important current-day priority, given the ambitions set out in the Sustainable Development Goals (SDGs). Increasingly, NPOs have taken up a role as conveners of such CSPs. Research on CSPs has, to date, often considered conveners as a ‘resource’ to the CSP, contributing to its effectiveness. In this study, we shift the focus towards the convener by considering a case of a ‘mission-driven convener’, an NPO that initiates CSPs as a strategy to realize its own sustainability objectives. Our explorative case study—comparing the NPO’s efforts across six countries in setting up national coffee platforms—reviews the concept of a mission-driven convener vis-à-vis established notions on convening and identifies which strategies it applies to realize a CSP. These strategies comprise productively combining certification-driven efforts with CSPs, combining process and outcomes of CSPs, and drawing on cross-level dynamics derived from outsourcing of convening work to local actors. With our study, we contribute to research on CSP conveners by offering an alternative interpretation to the relation between the CSP and the convener, attributing more agency to the convener as a mission-driven organization. Strengthening our understanding of CSPs and conveners is an important means to advance the Sustainable Development Goals (SDGs).