Background <p>Globally, law enforcement officers have tedious tasks of maintaining law and order, as well as protection of lives and properties. However, research output about the burden of mental health deficit and its associated predictors among police officers, especially in developing countries is scanty. Therefore, this study aimed to investigate the influence of occupational stress, personality, and job demand on the mental health of police officers in Ibadan, Nigeria. Hence, this study aimed to find out whether these variables independently and\or jointly influence the mental health of police officers in Ibadan.</p> Method <p>The study participants were 328 police officers from six Local Government Areas in Ibadan. A cross-sectional research design was adopted for this study, and a 75-item self-report questionnaire designed to assess socio-demographic variables and psychological factors was administered to the participants. Descriptive statistics were used to analyze the socio-demographic variables, while Pearson product-moment correlation and multiple regression were used to test the two hypotheses. Statistical significance was set at <i>p</i> &lt; .05.</p> Results <p>168 male and 160 female police officers participated in this study. 63 were constables, 43 were corporals, 41 were sergeants, 24 were 3rd sergeant majors, 94 were inspectors, 38 were assistant superintendents, 9 were deputy superintendents and 16 were superintendents. Their mean age was 36.49 ± 10.56. Occupational stress had a significant positive relationship with psychological distress, and the five personality dimensions had a significant negative relationship with psychological distress. All the independent variables in this study were joint significant predictors of mental health of police officers in Ibadan. However, occupational stress and four of the five personality dimensions were the only significant independent predictors of psychological distress among police officers in Ibadan. Job demand had no relationship, neither was it a significant predictor of psychological distress among police officers in Ibadan.</p> Conclusion <p>Police officers who experience elevated levels of occupational stress also reported psychological distress. Psychological distress among police officers in Ibadan is jointly predicted by occupational stress and some personality traits. These findings have implications for how officers perform their duties and the society’s safety. Hence, further research should focus on establishing causation between the independent variables and mental health and investigate other factors that can influence the mental health of police officers.</p>