Purpose: The purpose of this study was to characterize postpartum mental health service utilization in HIV-positive women. Methods: We identified 861 365 women who had a live birth delivery in Ontario, Canada and described their use of mental health services. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were reported to compare service use in HIV-positive and HIV-negative groups. Results: HIV-positive women (n=530) were more likely to access outpatient mental health services (aOR, 1.26; 95% CI, 1.03 to 1.55). Among those who accessed outpatient services, HIV-positive and HIV-negative women were equally likely to remain engaged in care (aOR, 1.24; 95% CI, .88 to 1.75). HIV-positive women were more likely to require a psychiatric ED visit or hospitalization (aOR, 2.74; 95% CI, 1.72 to 4.12). Conclusion: HIV-positive women were more likely to require a postpartum psychiatric ED visit or hospitalization despite using all outpatient mental health services in greater proportions.