The present study aims at exploring processual relationships between corporate sustainability predictors and sustainability performance, as informed by the Thai philosophy of Sufficiency Economy, and accordingly proposes a theory of corporate sustainability to fill in the fundamental gap in the literature. Based on a framework derived from the literature, multi-data collection methods and the framework approach to qualitative data analysis are adopted to explore the relationships at a sustainable enterprise in Thailand. Findings reveal six processual relationships leading to improving corporate sustainability performance directly and indirectly. Grounded upon seven established theories, the existing empirical literature and the findings of the present study, a coherent theory of corporate sustainability is developed to inform future theory building and guide future corporate sustainability research. Managerial implications and future research directions are discussed