Objective: This research aimed to explore the internal mechanism of transforming strategic orientation into the entrepreneurial performance of hidden champion start-ups. Methods: Based on the theory of opportunity-resource integration, the research adopted a longitudinal single-case study method to explore the opportunity-resource integration behaviors guided by the strategic orientation of Company A, and build the “orientation-behavior-performance” model. Results: The research found that internal and external factors influenced the selection of strategic orientation at each stage of hidden champion start-ups. Guided by different strategic orientations, hidden champion start-ups achieved rapid growth in entrepreneurial performance through corresponding opportunity-resource integration behaviors. Conclusion: Start-ups should flexibly choose a strategic orientation to guide the identification of opportunities and integration of resources according to the resources available at each stage.