Many industries face sustainability transformation challenges, including a quest for new business models. Business model innovation (BMI) has thus gained attention as an important strategic approach to proactively address sustainability transformation. However, BMI processes aimed at sustainability transformation remain under-researched, especially at the ecosystem level. This is significant gap because these processes may serve as instrumental frameworks for stimulating BMI. We therefore create an ecosystem-level business model innovation (EMI) process for sustainability transformation. The EMI process enables users to intentionally distance themselves from existing business models, imagine alternatives that fundamentally reconfigure value creation and capture, and experiment by connecting envisioned alternatives to actionable transformation scenarios. The EMI process consists of five steps: identifying drivers of change, constructing future images of alternative socio-technical environments, reconstructing ecosystem value propositions, proposing alternative ecosystem models, and experimenting. The EMI process is evaluated in an exemplary setting to illustrate its instrumentality and applicability.