Purpose: Non-Suicidal Self-Injury (NSSI), a highly prevalent behavior in adolescents, refers to the direct destruction of one’s body tissue without suicidal intent. To date, the prevalence of adolescent self-injury in South Korea and its associated factors remain unknown. This study aims to determine the prevalence of self-injury in Korean adolescents as well as its associated factors. Methods: We assessed 717 middle school students by means of an anonymous self-report survey. Information about demographic characteristics, lifestyle, anxiety and depression, self-esteem, and parenting behavior was obtained. Data were analyzed using x2 test, t-test and multiple logistic regression. Results: NSSI was reported by 8.8% of respondents. Univariate analyses showed associations of exposure to alcohol use, anxiety, depression, self-esteem, and parenting methods with self-injury. In multiple analyses, alcohol use, anxiety, and parental abuse were associated with lifetime self-injury. Conclusion: The rate of NSSI in the South Korea was found to be lower than those of other countries. As our study suggests that alcohol use, anxiety, and parental abuse are associated with lifetime self-injury, health care providers at school should take these factors into account when developing prevention and intervention programs for adolescents.