Social cognitive impairment is a core feature of schizophrenia, and deficits in facial emotion recognition stand out as especially severe and closely linked to functional outcomes. Growing evidence indicates that emotion recognition training can improve social cognitive functioning in this population. Accordingly, this study evaluates the efficacy of the Micro-Expression Training Tool (METT) in enhancing facial micro-expression detection in patients with schizophrenia and examines whether these training improvements generalize to broader domains of social cognition. We administered METT to 22 patients with chronic schizophrenia (SP), 32 healthy controls (HC), and 30 college students who received METT training (CS + METT) across seven assessment points: pre-test (T1), four weeks of training (T2–T5), post-test at one-week follow-up (T6), and one-month follow-up (T7). We also included an additional comparison group of 30 college students who did not receive METT training (CS–METT). At T1, T6, and T7, we assessed mentalizing capacity, macro-facial emotion recognition, and depressive and anxious moods. After controlling for age and executive function, all three METT-trained groups demonstrated significantly greater improvements in micro-expression recognition accuracy compared to T1, and they maintained these improvements at the one-month follow-up. Across the trained groups, participants also improved in macro-facial emotion recognition and mentalizing certainty over time. Although the SP group showed smaller overall improvements, only this group experienced a significant reduction in depressive mood. These findings suggest that METT effectively remediates social cognitive deficits, particularly emotion recognition, and that its benefits extend to mentalizing ability and mental health in individuals with schizophrenia.