Background: We previously published a systematic review evaluating retention in care after antiretroviral therapy treatment initiation among adults in low- and middle-income countries. We estimated retention at 36 months to be at 74% for studies published from 2008-2013. This review evaluates retention after the implementation of Universal Test and Treat in 2015. Methods: We searched PubMed, ISI Web of Science, Cochrane Database of Systematic Reviews, and EMBASE for studies published between January 1, 2017, to December 31, 2023 and searched conference abstract repositories from AIDS, IAS, and CROI from 2015-2023. Retention for each study was estimated using 1) simple averages and 2) interpolated for missing timepoints through the last reported timepoint. All-cause attrition for all participants who initiated first-line treatment in low- and middle-income countries was estimated. Overall retention rates were estimated using a generalized linear mixed model with a logit distribution using the interpolated data. Results: A total of 65 studies met our criteria for inclusion for the systematic review. Most studies came from Africa with very few from Europe and Asia. Very few studies reported retention past the first 12 months following treatment initiation. Across all studies, we estimated simple average retention with no interpolation of missing timepoints to be 72.6% at 12 months, 73.2%, at 24 months, 59.8% at 36 months, and 49.4% at 48 months. Utilizing a GLMM model, we estimated retention to be 86.0% at 6 months, 80.0% at 12 months, 82.0% at 24 months, 71.0% at 36 months, and 57.0% at 48 months. In comparison, our prior review conducted in 2015, estimated retention rates to be 91.0% at 6 months, 86.0% at 12 months, 79.0% at 24 months, 75% at 36 months, and 69% at 48 months. These results generally reflect retention at the initiating facility and omit the effect of unreported transfers. Conclusions: Retention in care at 36 months was estimated to be between 60% and 71%. Compared to results from our prior review, retention has stayed largely similar in the post-UTT era. Further research evaluating retention in other geographic areas (i.e., Latin America and the Caribbean, Europe, and Asia) is needed.