Background: Occupational Health and Safety Management Systems (OHSMS) enhance organizational performance. Internal audits are key to assessing their implementation and effectiveness in safeguarding the safety and health of workers, as well as in preventing workplace accidents and occupational illnesses. Internal auditing within organizations is vital for promoting continuous improvement of the management system. Objective: This study aims to evaluate the significance of internal auditing in improving organizational performance. Method: A survey was conducted involving organizations, both with and without the implementation of ISO 45001:2018. Results: The level of confidence in internal auditing for organizational success is positively influenced by ISO 45001:2018 certification, particularly among certified organizations where trust levels are higher. Certified organizations also tend to exhibit higher average ratings of organizational performance. Employees of larger companies perceive performance more favorably compared to those of micro and small companies. The level of confidence in internal auditing success significantly impacts the perceived importance of each benefit and its contribution to organizational performance. Conclusion: These findings contribute to understanding the implementation of OHSMS in organizations and underscore the critical role of internal auditing in enhancing organizational performance.