Purpose <p>This study examined the organizational, technological, and environmental factors influencing the use of electronic health record (EHR) systems in public health facilities in Tanzania. It applied the Technology-Organization-Environment (TOE) framework to identify key enablers and constraints of system usage.</p> Methods <p>A cross-sectional mixed-methods approach was adopted. Quantitative data were collected from 251 healthcare workers across public facilities using structured questionnaires. Binary logistic regression was used to assess associations between TOE domains and reported EHR usage. Qualitative insights were gathered through key informant interviews with facility managers and ICT officers, and were analyzed thematically using NVivo.</p> Results <p>Organizational factors, particularly staff training and workflow integration, showed strong statistical associations with EHR usage. Technological factors, such as infrastructure adequacy and the availability of technical support, also emerged as significant predictors. Environmental factors, including the policy environment and donor support, were not statistically significant; however, they were highlighted in the qualitative findings as influential. The integration of results highlighted organizational readiness as the strongest determinant of consistent EHR system use in this context.</p> Conclusions <p>Improving EHR usage in Tanzania’s public health facilities requires prioritization of staff training, leadership support, and infrastructural readiness. While national policies and donor engagement shape the broader implementation landscape, internal facility-level factors have a stronger direct influence on uptake. These findings contribute to a deeper understanding of digital health adoption in low-resource settings and offer practical recommendations for scaling EHR systems.</p>