BACKGROUND: Traditional MBSR or MBTC programs do not delve deeply enough into emotional regulation, which is especially relevant in oncological patients. The aim of this study was to analyze the benefits of a mindfulness-based emotion regulation program in adult oncological patients. METHOD: Psycho-oncologists from the AECC developed a mindfulness-based emotion regulation program. The Five Facet Mindfulness Questionnaire (FFMQ), Trait Meta-Mood Scale (TMMS), and Hospital Anxiety and Depression Scale (HADS) were administered before and after the program. A single-group pre-post test design with repeated measures was employed, utilizing the General Linear Model. RESULTS: Ninety-seven adult cancer patients completed the pre- and post-program assessments. Statistically significant improvements were observed in all FFMQ subscales, increased clarity of emotional discrimination, mood repair, and statistically significant reductions in anxiety and depressive symptoms. CONCLUSIONS: Regardless of the phase of the disease, the results of this study suggest that emotional regulation may improve and anxiety and depressive symptomatology decrease after a mindfulness-based emotion regulation program in oncological patients.