Background: We evaluated the prevalence of sexualized drug use (Chemsex) and its association with moderate/high risk for substance use disorders and HIV sexual risk behavior among men who have sex with men (MSM). Methods: We conducted a cross-sectional web-based survey among MSM from Rio de Janeiro (Brazil). The Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) was used to screen people at moderate/high-risk for substance use disorders. Individuals found to be using substances in the prior three months were asked if they used before/during sex. Sexualized drug use was classified into: no sexualized drug use, sex using only alcohol (alcohol-sex), sex using only illicit drugs (drug-sex) and sex using alcohol and illicit drugs (alcohol-drug-sex). The questionnaire included questions about sociodemographic, HIV status/prevention and risk behavior. A multinomial regression model was performed to assess the factors associated with sexualized drug use. Results: Overall, 1048 MSM completed the questionnaire; median age was 29 years. Prevalence of alcohol and illicit drug use in previous 3 months was 89 % and 49 %, respectively. Most MSM (64 %) reported sexualized drug use: 28 % alcohol-sex, 9 % drug-sex and 27 % alcohol-drug-sex. Median ASSIST scores were higher among those reporting sexualized drug use compared to no use. All HIV sexual risk behavior variables presented increasing prevalence across the outcome categories. In the adjusted multivariate model, having moderate/high-risk for substance use disorders were associated with sexualized drug use. Conclusions: MSM reporting sexualized drug use should receive brief intervention for substance use disorders and be evaluated for combination HIV prevention strategies including PrEP.