Investigating corporate strategy in fragile, post-conflict states presents significant methodological hurdles. Conventional quantitative approaches often fail to capture the contextual nuance, while purely qualitative studies lack statistical generalizability. This paper argues for and demonstrates the efficacy of a sequential explanatory mixed-methods design (QUAN -> qual) to overcome these challenges. It examines the complex process of adaptive innovation how a multinational corporation (MNC) can transform the profound liabilities of a fragile market into a sustainable competitive advantage. Using the exemplary case of MTN South Sudan, this study first establishes a robust quantitative model based on survey data from 391 employees across three sectors. This model, analyzed via Structural Equation Modeling (SEM), identifies marketing (β = 0.34, p < 0.001) and product innovation (β = 0.31, p < 0.001) as the most significant predictors of corporate performance. The second, qualitative phase uses these statistical findings as a scaffold for in-depth interviews with MTN’s key decision-makers. This qualitative inquiry reveals the underlying mechanisms and strategic logic that the numbers alone cannot explain: how process innovation is redefined as resilience, how product localization creates market dominance from institutional voids, and how marketing becomes an exercise in grassroots trust-building. The methodological contribution of this paper is its demonstration of how a rigorously integrated mixed-methods approach can provide a holistic, validated, and deeply insightful understanding of strategic phenomena in data-scarce, high-uncertainty environments, thereby offering a valuable template for future international business research in similar contexts.