Risky sexual behavior is a major health problem in Ethiopia. Some risky sexual behaviors among University students are early sexual debut, having multiple sex partners, and unprotected sex that makes them vulnerable to many health problems such as unintended pregnancy, and sexually transmitted infections worldwide particularly in Ethiopia. The objective of the study was to assess the prevalence and determinants of risky sexual behaviors among Bahir Dar University students. A survey cross-sectional study was conducted involving quantitative and qualitative methods. To get the required sample of students, the study utilized a multistage cluster sampling technique. The data were collected using a self administered questionnaire. The study employed univariate, bivariate, and multivariate analytical methods. The qualitative part involved five interviews selected purposively. The qualitative data were analyzed by thematic areas. From the total respondents, 132(40.2%) ever had sexual intercourse and the mean age at first sexual intercourse was 18.6 years. About 37.5% of respondents head risky sexual behaviors. In multivariate analysis regarding multiple sexual partners, years of study, monthly income, living arrangement, ever use substance, watching pornography and discussion with parents significantly predicted multiple sexual partners. In multivariate analysis, monthly income, living arrangements, years of study, substance use, attending night clubs, peer pressure, and religiosity significantly predicated risky sexual behaviors. The prevalence of risky sexual behaviors among Bahir Dar University students was high. Therefore, life skills training is recommended to diminish peer pressure among students. Interventions should be designed to reduce substance use, and attending night clubs are recommended. Keywords: Risky Sexual Behaviors, Determinants, University student, Bahir Dar, Ethiopia