ABSTRACT This study investigates the interplay between Customer Centricity (CC), Corporate Purpose (CP), quantified by the Purpose Strength Index (PSI), and Corporate Sustainability (CS), as evidenced by Organizational Citizenship Behaviors (OCB). Survey data from 2607 employees across diverse sectors were used to assess how CC enhances CS and the moderating role of PSI on the relationship between CC and different dimensions of OCB. Findings reveal a direct, positive correlation between CC and CS, significantly boosting extra‐role, social, and environmental behaviors. Moreover, while the PSI promotes social and environmental engagement, its influence on extra‐role behaviors appears minimal. This research provides new insights into the role of marketing strategies in promoting CS and offers a framework that merges customer‐centric and purpose‐driven approaches to sustainability. Our study contributes to the literature by highlighting the strategic importance of aligning CC with CP to strengthen CS, underpinning significant theoretical and practical advancements in sustainable practices.