<p>Given that mental health problems among children and adolescents are rising, mental health literacy (MHL) is increasingly becoming an important competency for teachers. Although systematic reviews and meta-analyses on teacher mental health knowledge and MHL programs have been done in the past, these reviews do not include qualitative studies on teacher MHL. To obtain a more comprehensive picture of the state of knowledge on teacher MHL, we conducted a narrative review of qualitative studies in teacher MHL from 2014 to 2024. A total of 19 studies were reviewed. We conducted a narrative synthesis of these studies and found the following themes: (1) teachers’ understanding of mental health problems; (2) teachers’ mental health-related roles; (3) barriers and facilitators in fulfilling mental health-related roles; and (4) MHL in teacher education and professional development. We then provided a critical reflection and discussion of the findings, where we identified the research gaps and provided suggestions for practice and future research directions.</p>