PURPOSE: The objective of this study was to evaluate the effectiveness of a shortened version of Mindfulness-integrated Cognitive Behavior Therapy (MiCBT) in managing pain and psychological distress (including depression, anxiety, and stress), improving equanimity, hope, and post-traumatic growth in patients with Stage I-III breast cancer undergoing chemotherapy. METHODS: A total of 42 women were randomly assigned to either an intervention group (n = 21) or a treatment-as-usual (TAU) (n = 21). All participants completed a battery of assessments for pain, emotional distress, hope, equanimity, and post-traumatic growth before and after the intervention, as well as at the 2-month follow-up. The intervention consisted of a short (4-week) MiCBT program, which involved progressive muscle relaxation, mindfulness of breath, body scanning, and the mindfulness-based interoceptive exposure task (MIET) for pain. The program was conducted over four consecutive weeks. RESULTS: Compared with the TAU group, at post-treatment, the MiCBT group experienced larger and significant reductions in pain (d = 1.58), psychological distress (d = .99), depression (d = 1.59), anxiety (d = 1.13), and stress (d = 1.68), as well as improvements in equanimity (d = 1.61), hope (d = 1.06), and post-traumatic growth (d = .6) (p's < .5). These differences remained significant at 2-month follow-up. CONCLUSION: This study provides preliminary evidence that a four-week MiCBT intervention can improve the daily experiences of women with BC undergoing chemotherapy. Further research using larger samples and active control is needed to determine the generalizability of the results.