While risky sexual behaviours related to illicit drug use among street youth have been explored, the impacts of alcohol use have received less attention. This longitudinal study examined hazardous alcohol use among a population of street-involved youth, with particular attention to sexual and drug-related risk behaviours. Data were derived from the At-Risk Youth Study, a prospective cohort of street-involved youth in Vancouver, Canada. The outcome of interest was hazardous alcohol use defined by the US National Institute on Alcohol Abuse and Alcoholism. We used generalized estimating equations (GEEs) analyses to identify factors associated with hazardous alcohol use. Between 2005 and 2014, 1149 drug-using youth were recruited and 629 (55%) reported hazardous alcohol use in the previous 6 months during study follow-up. In multivariable GEE analyses, unprotected sex (adjusted odds ratio [AOR] = 1.28, 95% confidence interval [95% CI] = 1.12–1.46) and homelessness (AOR = 1.35, 95% CI = 1.19–1.54) were independently associated with hazardous alcohol use (all p < .001). Older age (AOR = 0.95, 95% CI = 0.92–0.99), Caucasian ethnicity (AOR = 0.74, 95% CI = 0.61–0.90), daily heroin use (AOR = 0.53, 95% CI = 0.42–0.67), daily crack cocaine smoking (AOR = 0.73, 95% CI = 0.59–0.91), and daily crystal methamphetamine use (AOR = 0.52, 95% CI = 0.42–0.64) were negatively associated with hazardous alcohol use (all p < .05). In sub-analysis, consistent dose–response patterns were observed between levels of alcohol use and unprotected sex, homelessness, and daily heroin injection. In sum, hazardous alcohol use was positively associated with unsafe sexual behaviour and negatively associated with high-intensity drug use. Interventions to address hazardous alcohol use should be central to HIV prevention efforts for street-involved youth.