Objective There is currently no structured interview tool developed that comprehensively evaluates self-injurious thoughts and behaviors (SITB) in Korea. The Self-injurious Thoughts and Behaviors Interview (SITBI) collectively measures suicidal ideation, plans, gestures, attempts, and non-suicidal self-injuries (NSSI). The SITBI’s reliability and validity have been established with it being widely used in English speaking countries. This study evaluated the psychometric validity of the Korean version of the SITBI (SITBI-K). Methods The SITBI’s validity as a diagnostic assessment tool for NSSI and suicidal behavior disorder (SBD), as defined by the Diagnostic and Statistical Manual of Mental Disorders-5th edition, was examined. Analyses were performed on 108 university students reporting experiences of suicidal thoughts and behaviors (female 84.26%, mean age=22.10, ±SD 3.33). Results The SITBI-K displayed excellent interrater reliability, with a credible test-retest reliability at two months. Construct validity examined the correlation between the SITBI-K’s modules and approved the self-report results. Appropriate convergent and discriminant validities were obtained for suicidal ideation, plans, gestures, attempts, and NSSI. Conclusion The SITBI-K showed excellent psychometric validity at a level comparable to the original. Its clinical utility for both NSSI and SBD diagnoses was confirmed.