["Business Strategy and the Environment, Volume 35, Issue 4, Page 5926-5954, May 2026. ", "\nABSTRACT\nThe agri‐food industry faces major sustainability challenges, requiring a shift in companies' approach. Circular economy principles offer a promising path by enhancing resource efficiency, reducing waste, and valorizing by‐products. However, the integration of sustainability and circularity practices remains limited, especially in developing effective, sector‐specific assessment models. This study addresses the gap by proposing a novel self‐assessment framework based on mixed methods, to evaluate sustainability and circularity performance. It combines ESG dimensions with 10 circular R‐strategies, offering a dual‐level assessment. Legitimacy theory underpins the framework, highlighting that firms pursue sustainable and circular practices not only for compliance but also to gain social acceptance. The framework is validated through a multiple case study of three agri‐food firms. Results show that circularity is not always equivalent to sustainability, revealing differing levels of strategy adoption. This research contributes a comprehensive, practical tool to support sustainable innovation and measure circularity in agri‐food.\n"]