Purpose: This study aimed to identify trends in contraceptive use and methods, as well as the influencing factors among Korean adolescent girls with sexual intercourse experience.Methods: Secondary data analysis was performed using data from the 2013−2022 Youth Health Behavior Online Survey. Participants were 9,562 adolescent girls who had experienced sexual intercourse in middle and high schools in Korea. Descriptive statistics, the chi-square test, the Cochran-Armitage trend test, and logistic regression were used for data analysis.Results: The reported prevalence of consistent contraceptive use during sexual intercourse significantly increased from 27.0% in 2013 to 46.1% in 2022 (p<0.01). The rate of modern contraceptive use increased from 79.4% in 2013 to 84.8% in 2022 (p for trend <0.01). Factors influencing contraceptive use included age, school type by sex, academic performance, economic status, residential type, lifetime smoking, and sexual education. Factors influencing modern contraceptive use included school type by sex, economic status, residential type, and lifetime smoking.Conclusion: The results of this study indicate that more than half of the adolescent girls with sexual experience do not consistently use contraception, and some of them use unreliable contraceptive methods. Efforts are needed to improve modern contraceptive use among adolescent girls.