Industrial symbiosis is a key enabler of the circular economy, fostering cross-sector collaboration for the reuse of energy, materials, and resources. However, the implementation and scaling of industrial symbiosis solutions are often constrained by differences in maturity, stakeholder readiness, and contextual suitability. This paper presents a stakeholder-driven Multicriteria Decision Analysis methodology developed within the Horizon Europe-funded SYMBA project (101135562) to evaluate and prioritise industrial symbiosis solutions in bio-based industrial ecosystems across Europe. The framework assesses over 150 industrial symbiosis solutions using five readiness dimensions and weighting factors co-created through iterative engagement with internal and external stakeholders. The methodology enables the classification of solutions by maturity and provides targeted implementation guidance, offering a transparent and replicable decision-support tool to advance industrial symbiosis.