Objectives: Stigma toward people with mental health problems (MHP) in primary health care (PHC) settings is an important public health challenge. Research on stigma toward MHP is relatively scarce in Chile and Latin America, as are instruments to measure stigma that are validated for use there. The present study aims to validate the Opening Minds Scale for Health Care Professionals (OMS-HC) among staff and providers in public Chilean PHC clinics, and examine differences in stigma by sociodemographic characteristics. Methods: 803 participants from 34 PHC clinics answered a self-administered questionnaire. Confirmatory factor analysis was completed. Average 15-item OMS-HC scores were calculated, and means were compared via t-test or ANOVA to identify group differences. Correlations of OMS-HC scores with other commonly used stigma scores were calculated to evaluate construct validity. Results: The 3-factor OMS-HC structure was confirmed in this population. The average OMS-HC (α = 0.69) score was 34.55 (theoretical range 15–75). Significantly lower (less stigmatizing) mean OMS-HC scores were found in those with additional training and/or personal experience with MHP. Conclusion: The validated, Spanish version of OMS-HC can be of use to further research stigma toward MHP in Chile and Latin America, advancing awareness and inspiring interventions to reduce stigma in the future.