This study investigates the impact of organization’s social sustainability initiatives on supply chain performance, with organization’s size as a moderating factor. Data was collected via a survey of supply chain management professionals and analyzed using Partial Least Squares-Structural Equation Modelling (PLS-SEM), with performance measured through the On-Time-In-Full (OTIF) metric. The findings reveal that social sustainability initiatives, particularly those focused on employee welfare, significantly enhance supply chain performance. This supports the theory that social sustainability directly influences supply chain costs and performance, independent of organizational size. The study offers practical insights for supply chain professionals, emphasizing the role of employee welfare in improving operational outcomes and contributing to sustainable development goals. This research fills a critical gap in the literature by quantitatively linking social sustainability with supply chain performance, providing new insights into how these initiatives can drive organizational success.