Risky sexual behavior can be described as deliberate engagement in all actions that can expose the students to sexually transmitted infections and early pregnancy. It is associated with early sexual activity having multiple sexual partners, peer pressure, exposure to pornography, substance use, lack of communication on sex with parents, lack of sexuality education etc. Despite measures put in place to control the spread of HIV/AIDS, the incidence is still very high and this is because of increase in sexual risky behavior among students. This study was aimed at assessing risky sexual behaviours among public senior secondary school students in Ikenne LGA Ogun State.rnThis study adopted the descriptive survey research method of ex-post facto type. The population was 418 public senior secondary school students in Ikenne Local Government of Ogun State, Nigeria. Sample size was determined using Leslie Kish formular and proportional stratified random sampling technique was adopted to select 418 students for the study. A researcher self-administered questionnaire was used to collect data on factors associated with risky sexual behaviours among public senior secondary school students. Face and content validity of the instruments was ascertained by presenting it to the supervisor and expert in the field. Reliability of the questionnaire was determined using Cronbach alpha and co-efficient was 0.8. Data were processed using statistical package for the social sciences version 21.0. Five hypotheses were tested at 0.05 level of confidence.rnThe results of this study revealed that students' exposure to pornography (t-value = 3.870, f(1,410) = 3.762, p = .003), peer pressure (R =.469, R2 adj. = .220, f(1,410) = 9.075; P = .000), sexual activity (R =.427, R2 adj. = .182, f(1,410) = 3.756; P = .000), and students' risky sexual behaviour (R =.561, R2 adj. = .311, F (1,410) = 4.924; P = 0.000) significantly influenced students' risky sexual behaviour. However, drug use and abuse (R =.267, R2 adj. = .033, f(1,410) = 2.093; P = .067) was found to be insignificant in influencing the students' risky sexual behaviour.rnThe study concluded that there is a high prevalence of risky sexual behaviours among public senior secondary school students. Also, drinking alcohol, watching pornography, peer influence and no discussion on sexual reproductive issues with parents were factors that significantly increase the risk of risky sexual behaviour among students. The study recommended that it is very important to design school, parent and community-based intervention program to eliminate the situation which give way for student’s participation in risky sexual behavior.