Suppressing HIV viral loads to undetectable levels is essential for ending the HIV/AIDS epidemic. We evaluated randomized controlled trials aimed to increase antiretroviral medication adherence and promote undetectable viral loads among people living with HIV through November 22, 2019. We extracted data from 51 eligible interventions and analyzed the results using random effects models to compare intervention effects between groups within each intervention and across interventions. We also evaluated the relation between publication date and treatment effects. Only five interventions increased undetectable viral loads significantly. As a whole, the analyzed interventions were superior to Standard of Care in promoting undetectable viral loads. Interventions published more recently were not more effective in promoting undetectable viral loads. No treatment category consistently produced significant increases in undetectable viral loads. To end the HIV/AIDS epidemic, we should use interventions that can suppress HIV viral loads to undetectable levels.