Objective: Although the recently developed mental health literacy scale showed significant score differences between general population and mental health professionals, to this date there is no published scale intended to specifically assess mental health literacy (MHL) in healthcare students. This study constructed a 26-item scale-based measure to assess multiple components of MHL and associated psychometric properties in a sample of medical and public health students of 11 universities in Taiwan. Methods: The development and validation of the scale comprised three phases: measure development, pilot testing (n = 32), and psychometric properties examination (n = 1294). Results: 26 items were generated for five factors: maintenance of positive mental health, recognition of mental illness, attitude to mental illness stigma, help-seeking efficacy, and help-seeking attitude. The scale demonstrated good content validity, internal consistency, and construct validity (factorial validity, convergent validity, discriminant validity, and known groups validity). Conclusions: The findings suggest that the Mental Health Literacy Scale for Healthcare Students (MHLS-HS) is a valid, reliable, and practical tool for identifying MHL gaps in medical and public health students. It has the potential to inform remedial curricular interventions for educators and evaluate intervention effectiveness.