Background: We investigated the prospective association between a brief self-report measure of engagement in human immunodeficiency virus (HIV) care (the Index of Engagement in HIV Care; hereafter "Index") and suboptimal retention and viral suppression outcomes. Methods: The Centers for AIDS Research Network of Integrated Clinical Systems cohort study combines medical record data with patient-reported outcomes from 8 HIV clinics in the United States, which from April 2016 to March 2017 included the 10-item Index. Multivariable logistic regression was used to estimate the risk and odds ratios of mean Index scores on 2 outcomes in the subsequent year: (1) not keeping ≥75% of scheduled HIV care appointments; and (2) for those with viral suppression at Index assessment, having viral load >200 copies/mL on ≥1 measurement. We also used generalized linear mixed models (GLMMs) to estimate the risk and odds ratios of appointment nonattendance or unsuppressed viral load at any given observation. We generated receiver operating characteristic curves for the full models overlaid with the Index as a sole predictor. Results: The mean Index score was 4.5 (standard deviation, 0.6). Higher Index scores were associated with lower relative risk of suboptimal retention (n = 2576; logistic regression adjusted risk ratio [aRR], 0.88 [95% confidence interval,. 87-.88]; GLMM aRR, 0.85 [.83-.87]) and lack of sustained viral suppression (n = 2499; logistic regression aRR, 0.75 [.68-.83]; GLMM aRR, 0.74 [.68-.80]). The areas under the receiver operating characteristic curve for the full models were 0.69 (95% confidence interval,. 67-.71) for suboptimal retention and 0.76 (.72-.79) for lack of sustained viral suppression. Conclusions: Index scores are significantly associated with suboptimal retention and viral suppression outcomes.