Background: Service delivery models for differentiated care provide a balanced approach to HIV services using longer dispensing intervals for patients who are stable and virologically suppressed. The paper aims to assess adherence to antiretroviral therapy (ART) and viral load suppression (VLS) among adolescents and young adults enrolled to multi-month dispensing (MMD) for ART prescriptions. Methods: This was retrospective cross-sectional analysis of routinely collected data from care and treatment clinics for adolescents and young adults living with HIV and initiated on antiretroviral therapy (ART), between 2016 to 2020 in 26 Tanzanian Regions. Descriptive statistics were used to summarize the covariates of study sample. Logistic regression was used to determine adjusted odds ratios (AOR) for the effect of MMD on VLS comparing 3-month dispensing (3MD) and 6- month dispensing (6MD) with the standard, one-month dispensing. Results: In 20676 stable clients on ART, 10373 (50.2%) were initiated on 3MD, 6951 (33.6%) on 6MD, and 3352 (16.2%) remained on one month standard of care (SOC). Those that received 3MMD had better adherence to ART (AOR=1.63, p<0.001) and greater VLS (AOR=3.88, P<0.001) than SOC. However, those that received 6MMD also had better adherence to ART (AOR=1.42, p=0.001) and higher VLS (AOR=1.65, p<0.001) than SOC. Conclusions: A large proportion of eligible clients were initiated on multi-month dispensing in either three- or six-month prescriptions with reduced clinical visits and extended ART refills. The study also validates that the shift to multi-month prescription schedules and provides evidence of better adherence to ART and viral load suppression.