Introduction Jamaica did not achieve the UNAIDS 90-90-90 targets in 2020. This study aimed to examine trends and factors associated with uptake of HIV treatment among people living with HIV (PLHIV) in Jamaica and to assess the effectiveness of revised treatment guidelines. Methods This secondary analysis used patient-level data from the National Treatment Service Information System. The baseline sample was 8147 PLHIV initiating anti-retroviral treatment (ART) between January 2015-December 2019. Descriptive statistics were used to summarize demographic and clinical variables and the primary outcome timing of ART initiation. Multivariable logistic regression was used to assess factors associated with ART initiation (same day vs 31+ days), using categorical variables for age group, sex and regional health authority. Adjusted odds ratios and 95% confidence intervals are reported. Results Most persons initiated ART at 31+ days (n = 3666, 45%) after the first clinic date or on the same day (n = 3461, 43%). Same day ART initiation increased from 37% to 51% over 5 years and was significantly associated with males (aOR = 0.82, CI = 0.74–0.92), 2018 (aOR = 0.66, CI = 0.56–0.77), 2019 (aOR = 0.77, CI = 0.65–0.92). late HIV diagnosis (aOR = 0.3, CI = 0.27–0.33) and viral suppression at the first viral load test (aOR = 0.6, CI = 0.53–0.67). ART initiation at 31+days was associated with 2015 (aOR = 1.21, CI = 1.01–1.45) and 2016 (aOR = 1.30, CI = 1.10–1.53) compared to 2017. Conclusion Our study shows that same day ART initiation increased between 2015–2019, however it remains too low. Same day initiation was associated with the years after Treat All implementation and late initiation before Treat All, providing evidence of the strategy’s success. In order to achieve the UNAIDS targets, there is a need to also increase the number of diagnosed PLHIV retained on treatment in Jamaica. Further studies should be conducted to understand important challenges to accessing treatment as well as differentiated care models to improve treatment uptake and retention.