Background: Electronic Health Record (EHR) systems have become important tools for improving healthcare operations and service delivery in public hospitals. However, the effectiveness of these systems in enhancing operational performance within Nigerian public hospitals remains underexplored, particularly regarding the roles of staff engagement and technological readiness.

Objective: This study examined the effect of EHR system effectiveness on operational performance in public hospitals in Lagos, Nigeria, while investigating the mediating role of staff engagement and the moderating role of technological readiness.

Methods: The study adopted a quantitative cross-sectional survey design grounded in the positivist philosophy. Data were collected from 306 healthcare professionals in selected public hospitals in Lagos State using structured questionnaires. Structural Equation Modelling (SEM) with SPSS 28 and AMOS 29 was used for data analysis.

Results: The findings revealed that EHR system effectiveness significantly improved operational performance (β = 0.31, S.E. = 0.07, p < 0.001). EHR system effectiveness also positively influenced staff engagement (β = 0.49, S.E. = 0.06, p < 0.001), while staff engagement significantly enhanced operational performance (β = 0.37, S.E. = 0.08, p < 0.001). The mediating effect of staff engagement was significant (β = 0.18, S.E. = 0.05, p < 0.001). Technological readiness significantly moderated the relationship between EHR effectiveness and operational performance (β = 0.21, S.E. = 0.06, p < 0.001) and directly influenced operational performance (β = 0.29, S.E. = 0.07, p < 0.001).

Conclusion: The study concludes that effective EHR systems, supported by engaged healthcare workers and strong technological readiness, significantly improve operational performance in public hospitals in Lagos, Nigeria.