Enterprises in Nigeria face persistent structural and governance impediments that constrain sustainable growth and development. Existing analyses often treat these challenges in isolation, lacking an integrated diagnostic tool for practitioners and policymakers. This paper develops and presents a novel diagnostic framework to systematically identify, categorise, and analyse the interconnected structural and governance challenges confronting businesses. It aims to provide a practical tool for holistic organisational assessment. The framework was constructed through a synthesis of institutional theory and strategic management literature, refined via iterative application to a longitudinal analysis of documented case studies and sector reports. The diagnostic process involves a multi-layered scoring system across defined challenge domains. Application of the framework reveals that governance deficiencies, particularly in transparency and board oversight, are not standalone issues but are critically entangled with structural weaknesses in infrastructure and access to finance. A dominant theme was the recursive relationship where poor governance exacerbates structural constraints, creating a self-reinforcing cycle. The diagnostic framework confirms the deep interconnectivity of business challenges in this context, demonstrating that effective intervention requires simultaneous attention to both structural and governance dimensions rather than addressing them sequentially. Enterprises should adopt the framework for internal auditing of vulnerability points. Policymakers are urged to design support programmes that condition structural assistance on verifiable improvements in corporate governance standards. diagnostic framework, corporate governance, structural constraints, business environment, institutional analysis This paper's primary contribution is the introduction of a novel, integrated diagnostic framework that enables the systematic mapping of interdependencies between structural and governance challenges, a significant advancement over previous siloed approaches.