Introduction: Transgender people are stigmatized in South Korea (hereafter Korea), where cultural expectations of a biologically-based, binary sex and gender system present fundamental challenges to those whose gender identity does not align with their birth-assigned sex. A growing international body of literature implicates gender minority stress as a key contributor to transgender mental health disparities, but little research has been conducted on this topic in Korea. As in other cultural settings, depression and suicidality are urgent public health concerns for transgender people in Korea, primarily for those who have not initiated gender affirming medical treatment (GAMT), such as cross-sex hormone therapy. In the current study, an international and interdisciplinary team of authors apply the lens of gender minority stress to elucidate the relationships between a key facet of gender minority stress, internalized transphobia (ITP), and outcomes of depressive symptoms and suicidality. Methods: Based on a cross-sectional survey of 207 Korean transgender adults, the current study evaluates the relationships between ITP and depressive symptoms, suicidal ideation, and suicide attempts. ITP was measured with an eight-item, Korean-language questionnaire adapted from the Gender Minority Stress and Resilience Measure through a translation and back-translation process. Results: Korean trans women and trans men mean (mean age = 26.4) were included in the analysis, most of whom had at least one experience of any GAMT. The findings of this study show that Korean transgender adults face similar public health concerns such as high prevalence of depressive symptoms, suicidal ideation, and suicide attempts. As predicted, ITP was significantly related to depressive symptoms, suicidal ideation, and suicide attempts. Conclusion: The authors suggest potential clinical, policy, and research applications, including institutional interventions, to address structural and cultural barriers to optimal mental health and GAMT as well as mental health interventions to reduce Korean transgender people's internalized negative beliefs about their gender identity.