This study employs a qualitative System Dynamics (SD) methodological approach, utilizing stakeholder workshops and interviews, to investigate the evaluation structure of biomass and coal co-firing integration in Indonesia's coal-fired power plants. The primary deliverable of this research is a validated conceptual model that serves as the foundation for a dynamic simulation framework and a subsequent policy roadmap. A key novel finding is the identification and stakeholder validation of specific feedback mechanisms unique to Indonesia's archipelagic context, including four reinforcing loops (R1-R4)—such as policy-driven cost efficiency tied to local subsidy schemes—and one critical balancing loop (B1) representing technical and supply chain bottlenecks, like feedstock variability. This Indonesia-centric SD framework structures the dynamic interactions between policy, economics, and logistics, accounting for constraints such as fragmented supply chains and regional disparities. It enables the testing of six tailored policy interventions, including incentives for biomass utilization, subsidy schemes for co-firing infrastructure, and carbon pricing. The resulting conceptual model and policy roadmap provide stakeholders with a practical tool for optimizing co-firing strategies to support Indonesia’s journey toward its net-zero emissions goal.