Background: Risky sexual behavior (RSB) is common among youths which predispose them to sexually transmitted infections. This study sets out to identify the factors associated with RSB among undergraduates in Osun state. Methods: The study design was descriptive cross sectional and a total of 550 respondents from two universities in Osun state were sampled using a multistage sampling technique, out of which data from 266 sexually experienced respondents was further analyzed. Data collected via a semi–structured self-administered questionnaire and analyzed using univariate, bivariate and multivariate analyses. Results: The 266 respondents consisted of 54.5% males and 45.5% females and larger percentage of them were in the age group 15-24years. Seven out of ten respondents (69.9%) were sexually active while 65.8% were involved in at least one RSB. Of the 266 respondents, 28.6% ever had concurrent multiple sexual partners, 15.8% used alcohol/drugs at last sex while 48.1% did not use condom at last sex. More males (71.7%), alcohol users (76.8%), drug users (78.0%), pornography watchers (82.7%), internet users (71.2%) respondents “not in good terms with mum” (86.7%) and “those whose mum doesn’t instruct them morally” (84.2%) were involved in RSB compared to their respective counterparts (p<0.05). However, there were no identifiable predictors of RSB on regression analysis. Conclusion: Risky Sexual Behavior is prevalent among undergraduates with males being more involved, among other associated factors. Concerned stakeholders should engage youths via behavioral change communication strategies so as to significantly reduce their involvement in RSB. Keywords: Behaviour; experienced; factors, risky; sexual undergraduates.