<p>Firms gain a competitive edge by integrating corporate social responsibility (CSR) into their operations and fostering organizational citizenship behaviour (OCB), which encourages reciprocity and benefits the organization as a whole. CSR is particularly significant in the food industry, where every stage of the supply chain impacts sustainability. Consequently, food companies implement CSR initiatives such as recycling programs and resource management strategies. These efforts depend on employee collaboration and, in turn, foster OCB. Drawing on social identity theory, this study examines the mechanism linking CSR and OCB, proposing that trust, identification, and engagement collectively form a sequential mediation effect in this relationship. Data were collected through questionnaires from 106 store employees at a food company, and the proposed model was analyzed using structural equation modeling. The results underscore the critical role of employee engagement—an underexamined factor in relevant studies—and confirm its full mediating effect in the sequential pathway. In line with recent literature, our findings suggest that firms can enhance OCB through CSR initiatives by embedding environmental, social, and governance (ESG) principles into daily operations. Additionally, companies should implement CSR communication programs aimed at employees to build trust, strengthen organizational identification, and deepen emotional engagement.</p>