Background: Mothers play an important role in the process of treating children's stuttering. Enhancing mothers’ psychological state through coping strategies and psychological hardiness based on schema therapy can significantly affect the mother-child relationship during the therapeutic process. Objectives: The present study aimed to investigate the effectiveness of schema therapy on the coping strategies and psychological hardiness of mothers with stuttering children in Kermanshah. Methods: The present quasi-experimental study employed a pre-test-post-test design with a control group. In this study, 30 mothers of stuttering children were selected through purposive sampling and randomly divided into two groups. Endler and Parker's coping strategies questionnaire and Kubasa's psychological hardiness questionnaire were used. Schema therapy, based on Young's schema therapy protocol, was used as the intervention in one group. Results: The average age in the schema therapy intervention group was 34.60 ± 6.28 years, and in the control group, it was 35.87 ± 6.38 years. The highest frequency of education level in both groups was at the diploma degree. Regarding family income (socioeconomic status), the average-level income was the most common in both groups. Statistical comparison of the pre- and post-test scores of task, emotion, and avoidance strategies, as well as the scores of commitment, challenge, and control components, showed statistically significant differences in the schema therapy group (P < 0.001). Conclusions: As the present findings showed, due to the significant role of mothers' interaction and reaction in managing the treatment process of stuttering children, schema therapy can be used to improve the coping strategies and psychological hardiness of mothers.