Introduction Despite, risky sexual behavior behaviors adversely affect the health of youth people, youth has been start sexual lives during teenager is increasing, thus youth has been engaged in risky sexual behaviors. However, almost all the previous studies are institutional based and did not considered out school youth. Therefore, this community based study among youth was implemented to identify sociodemographic determinants of risky sexual behaviors among youth. Methods The community based cross-sectional study design was conducted from March 15 to April 15, 2019, among youths. Data were extracted from data collected for project on assessments of common health problem and risky behaviors in central, north and west Gondar zone, Northwest Ethiopia. A bivariable and multivariable logistic regression model was fitted. Adjusted odds ratio with 95% confidence interval were used to determine the presence of an association between independent variables and risky sexual behavior. Results The overall prevalence of risky sexual behavior was 27.5%, 95%CI: (25–29). Age 20–24 years (AOR = 1.8,95% CI:1.3–2.5), female (AOR = 1.6,95%CI: 1.2–2.1), had no formal education (AOR = 1.9,95% CI:1.1–3.4), not schooling during data collection year (AOR = 1.8,95%CI:1.3–2.6), family wealth index status; lowest (AOR = 2.3,95%CI:1.3–3.9), low (AOR = 2.1,95%CI:1.2–3.5), medium (AOR = 1.9,95%CI:1.2–3.0) and high (AOR = 1.8, 95%CI:1.1–3.0), having common mental disorder (AOR = 2.0,95% CI: 1.4–2.7), and watching pornography materials (AOR = 1.6, 95%CI: 1.2–2.1) were factors associated with risky sexual behaviors. Conclusions Findings of this study revealed that one every four youths aged 15–24 years old had risky sexual behaviors. Hence, working on economic development of the family and prevention of violence can contribute to reducing risky sexual behavior among youths.