Objective: The objective was to identify validated instruments from the literature that assess the mental health of police officers. Methods: This is a systematic review of validated instruments used to assess the mental health of police officers. Searches were conducted in the MEDLINE, Web of Science, Scopus, Embase, CINAHL/EBSCO, and Virtual Health Library databases. This review follows the JBI Manual for Systematic Reviews and the PRISMA statement. The methodological quality of the articles and the risk of bias were assessed. Results: A total of 1530 studies were identified across the six databases, with 158 studies read in full by the authors after excluding duplicates and those that did not meet the inclusion criteria. The final 29 studies were analyzed for methodological quality and risk of bias using the AXIS and SFS-D tools. Conclusion: This review identified 27 self-administered validated instruments useful for assessing various mental health outcomes in police officers, with the most frequently used being the Police Stress Questionnaire. These findings may help guide security force administration, occupational health professionals, and mental health researchers in selecting and implementing psychometrically reliable instruments for screening the mental health of police officers.