This study aimed to develop and establish the efficacy of a life skills-based sexuality education programme for junior high school students that focused on prevention. A non-equivalent control-group pretest-posttest design was employed with 105 students in the first-year of junior high school participating. The experimental group received 10 sessions of a life skills-based sexuality education programme, and the control group received 10 sessions of the standard sexuality education, both provided during a home economics class. A comparison of the two groups' post-test scores showed that the experimental group scored significantly higher than the control group on sexual and reproductive health related knowledge (F = 58.50, p < 0.001) and life-skills (F = 11.52, p = 0.007). In addition, the experimental group showed a larger improvement in self-management skills for sexual health than did the control group (F = 9.32, p = 0.003). A life skills-based sexuality education programme increased life skills levels, knowledge about sexuality and sexual and reproductive health, and helped participants identify appropriate behaviours when facing a sexually risky situation. Results highlight the value of including an evidence-based and practice-oriented life skills-based sexuality education programme in the formal curriculum of junior high schools in Korea.