Background: Bipolar disorder is associated with chronic symptoms that impair cognitive abilities and executive functions. Objectives: The aim of this study was to investigate the effectiveness of a mindfulness intervention on elements of emotional self-regulation in patients with bipolar disorder. Methods: This research utilized a quasi-experimental design with pre-test and post-test assessments. The study population included patients with bipolar disorder who were referred to the rehabilitation and treatment center for chronic mental patients in Hayat from 2021 to 2022. A total of 30 participants were randomly selected and divided into two groups: an experimental group (15 participants) and a control group (15 participants). The experimental group underwent 8 sessions of mindfulness training, while the control group did not receive any intervention. The Emotional Self-Regulation Questionnaire (SRI-25) was administered for evaluation. Data analysis was conducted using multivariate analysis of covariance (MANOVA) in SPSS version 16. Results: The results of covariance analysis showed a statistically significant difference between the mean scores of the experimental and control groups in the components of emotional self-regulation after mindfulness training (P < 0.05). Thus, the experimental group demonstrated a significant increase in emotional regulation component scores compared to the control group after the eight mindfulness sessions (P < 0.05). Conclusions: Given the effectiveness of mindfulness training in enhancing the dimensions of emotional regulation, health practitioners are encouraged to use such interventions to improve emotional self-regulation in patients suffering from bipolar disorder.