Purpose: This study investigated the association between adolescent health behaviors (drinking, smoking, and drug use) and sexual inter-course, as well as the moderating effects of economic status, cohabitation with parents, and school type, among adolescents in Korea. Methods: Secondary data from the 16th Adolescent Health Behavior Survey (2020) were used. A total of 395 schools and 54,948 middle and high school students participated in the study. Complex sample frequency analysis, the Rao–Scott test, and complex sample logistic re-gression analyses were performed. Results: Sexual intercourse rates for men and women were 5.8% and 3.3%, respectively. Approximately 7.3% of high school students and 1.8% of middle school students reported having had sexual relations. Drinking (odds ratio [OR] = 3.15, 95% confidence interval [CI] = 2.82~3.52), smoking (OR = 6.75, 95% CI = 5.90~7.71), and drug use (OR = 3.03, 95% CI = 2.23~4.11) signifi-cantly increased the risk of sexual intercourse. Economic status and school type had moderating effects on the association between drink-ing and sexual intercourse. Conclusion: Adolescent drinking, smoking, and drug use are associated with a higher risk of sexual experience. Thus, to reduce this risk, controlling alcohol consumption, smoking, and drug use is necessary. In addition, programs for healthy lifestyles and sexual intercourse should be differentiated according to the school type and the economic conditions of the adolescents’ households.