Background Borderline personality disorder is linked to challenges such as low career success, relationship difficulties, increased conflicts, and lower life satisfaction, often due to poor distress tolerance and high aggression. Psychotherapy is the main treatment, with medication as a supplementary option. This study investigates the effectiveness of imagery rescripting in reducing aggression and improving distress tolerance compared to medication-as-usual. Method The study used an experimental design with pre-tests and post-tests and included a control group. Thirty-fo individuals with borderline personality disorder were matched and assigned to experimental and control groups. Over 5 weeks, the experimental group received one weekly session of mental imagery reconstruction along with medication-as-usual, while the control group only received medication-as-usual. Findings The results indicated that imagery rescripting along with medication can be effective in reducing aggression from 103.53 to 86.93 (mean = 16.60, SD = 6.23, p = 0.000) and increasing distress tolerance from 26.86 to 38.59 (mean = 11.73, SD = 5.37, p = 0.000) in people with borderline personality disorder, and medication alone is also effective in reducing aggression from 104.64 to 85.78 (mean = 18.85, SD = 9.13, p = 0.000). However, there was no significant difference in the aggression scale between the two groups (mean = 1.14, SD = 3.13, p = 0.717). Conclusion The imagery rescripting technique may help individuals with BPD reduce self-directed anger and improve emotional tolerance by addressing the roots of unpleasant emotions. This technique shows promise in enhancing distress tolerance and potentially decreasing self-harming behaviors.