Background: Youth psychiatric hospitalizations have been associated with negative outcomes, including premature death and post-discharge self-harm. Identifying risk factors for youth psychiatric hospitalization is crucial for informing prevention strategies. We aimed to evaluate the risk factors for psychiatric hospitalizations among low-income youth in Brazil. Methods: This cohort study used interpersonal violence and psychiatric hospitalization data linked to the 100 Million Brazilian Cohort baseline. We considered 9 985 917 youths aged 5-24 years who enrolled at the baseline, between 2011 and 2018. We estimated the incidence rate (IR) with 95% confidence interval (CI) for psychiatric hospitalization by calculating the number of hospitalizations per person-year in 100 000 individuals at risk. The multilevel, multivariate Cox proportional hazards regression estimated the hazard risks (HR) with 95% CI for psychiatric hospitalization. Results: The IR of psychiatric hospitalization was 12.28 per 100 000 person-years (95% CI, 11.96-12.6). Interpersonal violence victimization was the main risk factor for youth psychiatric hospitalization (HR, 5.24; 95% CI, 4.61-5.96). Other risk factors for psychiatric hospitalization included living with the oldest family member who had low education (HR, 2.51; 95% CI, 2.16-2.91) or was unemployed (HR, 1.49; 95% CI, 1.36-1.62), living with seven or more family members (HR, 1.84; 95% CI, 1.49-2.26) and being male (HR, 1.28; 95% CI, 1.21-1.36). Conclusions: Urgent action is needed to prevent youth from suffering violence. Addressing this may alleviate the mental health burden in developmental ages, benefiting youth, families and the government through reduced costs in preventable psychiatric hospitalizations.