Forgiveness is an interdisciplinary topic. The very fact that the concept of forgiveness is found in different spiritual traditions indicates that the act of forgiving is of special importance to human social functioning both within and across cultures. With this in mind, psychologists conduct research on the determinants of forgiveness and its impact on the psychosocial functioning of individuals. The predictors of forgiveness include, among others, personality traits. However, researchers emphasize that the impact of personality on the willingness to forgive is mediated by numerous other variables. An analysis of psychological literature as well as clinical and therapeutic experience suggest that early maladaptive schemas (EMS) may be one such variable. Thus, the main goal of the present study was to examine whether EMS played an intermediary role in relationships between personality traits and forgiveness in Polish adults. Two hundred and forty adults aged 20 to 59 years were surveyed. Four measures were used: (a) the NEO-Five Factor Inventory (NEO-FFI), (b) the Personality Inventory for DSM-5 (PID-5-SF), (c) the Young Schema Questionnaire (YSQ-S3), and (d) the Heartland Forgiveness Scale (HFS). The analyses revealed a number of statistically significant relationships. Among others, it was confirmed that EMS mediated the relationships between four (out of 10) personality traits and forgiveness. Mediation relationships were found for neuroticism (normal personality) and the dysfunctional personality traits of negative affectivity, detachment, and psychoticism.