This article examines how business model transformation toward sustainable development can support long-term value creation and financial resilience in mature, highly competitive sectors. In saturated, low-margin markets, cost leadership alone no longer ensures stable earnings or predictable cash flows. Using Lidl as a case study in the European food retail industry, the article investigates how a leading discount retailer has reconfigured its business model to stabilize performance under these conditions. The study relies on a multi-source qualitative analysis combining financial and industry press, corporate communications, and market research data. Key Success Factors are identified through thematic content analysis and mapped onto the Sustainable Business Model Canvas (SBMC). The results show that Lidl’s financial resilience and sustainable performance stem from a coherent configuration of five mutually reinforcing mechanisms: (a) value differentiation through private-label brands, (b) operational excellence, (c) strong local embeddedness, (d) disciplined capital allocation, and (e) CSR integration. Together, these mechanisms contribute to revenue quality, margin stability, and downside-risk mitigation. This article contributes to both the ESG investment literature and global strategy research by showing how the integration of sustainability into coherent business model architectures supports long-term competitive advantage, investment attractiveness, and performance stability across national contexts.