The inspiration of this study pertains to the problem of identifying and prioritizing sustainability impact assessment criteria of local organic food supply chains. Scoring models are often regarded as the most promising method of handling this increasingly important sector, but the literature on sustainability assessment concepts is only emerging. Multi-Criteria Decision Analysis based techniques such as Fuzzy Analytic Hierarchy Process (FAHP) appear practically appealing, as a way to develop commercially viable arrangements to develop sustainability assessment decision models. The first phase of our study identifies sustainability assessment criteria for organic food supply chains through literature review and expert panel interviews. Literature identifies environmental sustainability, economic sustainability and societal sustainability as the main criteria and a set of sub-criteria under each main criterion. The second phase develops a FAHP survey questionnaire for criteria analysis and weighting. Sub criteria such as Reduction of Food Waste, Reduction of Impact from Transportation and Emissions and Transparency and Traceability receive highest weights under economic, environmental and social criteria. Our research provides a structured decision-making framework which can be a valuable tool for strategic planning, enabling targeted interventions to improve farmers' resilience and support the growth of the organic sector in Sri Lanka.