Importance: Viral suppression of HIV is an important treatment goal to decrease morbidity, mortality, and risk of transmission to others. Objective: To characterize longitudinal HIV viral load outcomes among women enrolled in the Women's Interagency HIV Study (WIHS). Design, Setting, and Participants: A prospective cohort study of HIV-positive women with semiannual study visits and a minimum of 5 follow-up visits was conducted from 1994 to 2017. The WIHS sites included in this analysis are in Brooklyn and Bronx, New York; Chicago, Illinois; San Francisco, California; and Washington, DC. Main Outcomes and Measures: Women were categorized into groups based on their probability of achieving viral load suppression below 200 copies/mL using logistic trajectory modeling. Multinomial regression analysis was used to identify factors associated with placement in the group with the highest probability of viremia. Results: At baseline, the mean (SD) age of the 1989 women was 36.9 (8.0) years, mean CD4+ T-lymphocyte count was 467/mm3, median (interquartile range) HIV RNA was 6200.0 (384.5-41 678.0) copies/mL, and 1305 women (65.6%) were African American. Three trajectory groups were identified with low (568 [28.6%]), intermediate (784 [39.4%]), and high (637 [32.0%]) probability of viremia above 200 copies/mL. The mean (SD) cumulative years of viral suppression were 18.7 (4.0) years, 12.2 (3.1) years, and 5.8 (2.9) years in the respective groups. Factors associated with high probability of viremia included younger age (odds ratio [OR]. 0.99; 95% CI, 0.98-0.99; P = .03), African American race (odds ratio [OR], 2.43; 95% CI, 1.75-3.37), P < .001), Hispanic race/ethnicity (OR, 1.50; 95% CI, 1.03-2.19; P = .04), increased levels of depressive symptoms (OR, 1.17; 95% CI, 1.01-1.36; P = .03), drug use (OR, 1.23; 95% CI, 1.01-1.51; P = .04), lower CD4+ T-lymphocyte counts (OR, 95% CI, 0.82; 0.80-0.85; P < .001), and unstable housing (OR, 1.25, 95% CI, 1.03-1.50; P = .02). Between 2015 and 2017, 71.2% of women demonstrated sustained viral suppression: 89.6% (310 of 346) of those with low viremia, 83.4% (346 of 415) with intermediate, and 35.2% (112 of 318) with high probability of viremia. Conclusions and Relevance: This longitudinal approach suggested that the probability of viremia decreased substantially over time for most participants, including among women with earlier histories of incomplete viral suppression. The findings from this study suggest that continued efforts are needed to address mental health, social, behavioral and structural factors that were identified as associated with high probability of HIV viremia over time.