Alcohol use is highly prevalent globally with numerous negative consequences to human health, including HIV progression, in people living with HIV (PLH). The HIV continuum of care, or treatment cascade, represents a sequence of targets for intervention that can result in viral suppression, which ultimately benefits individuals and society. The extent to which alcohol impacts each step in the cascade, however, has not been systematically examined. International targets for HIV treatment as prevention aim for 90 % of PLH to be diagnosed, 90 % of them to be prescribed with antiretroviral therapy (ART), and 90 % to achieve viral suppression; currently, only 20 % of PLH are virally suppressed. This systematic review, from 2010 through May 2015, found 53 clinical research papers examining the impact of alcohol use on each step of the HIV treatment cascade. These studies were mostly cross-sectional or cohort studies and from all income settings. Most (77 %) found a negative association between alcohol consumption on one or more stages of the treatment cascade. Lack of consistency in measurement, however, reduced the ability to draw consistent conclusions. Nonetheless, the strong negative correlations suggest that problematic alcohol consumption should be targeted, preferably using evidence-based behavioral and pharmacological interventions, to indirectly increase the proportion of PLH achieving viral suppression, to achieve treatment as prevention mandates, and to reduce HIV transmission.