Introduction: According to the World Health Organization (WHO), the recommended rate of cesarean section (CS) is approximately 5–15% of all live births. In Indonesia, cesarean section rates are estimated to be approximately 11% in public hospitals and may exceed 30% in private hospitals. The increasing number of cesarean deliveries has contributed to a higher incidence of postoperative pain, which may interfere with maternal recovery, early mobilization, breastfeeding, and mother–infant bonding. Non-pharmacological pain management strategies, including deep breathing relaxation techniques and classical music therapy, have been widely utilized as complementary nursing interventions to reduce postoperative pain by promoting muscle relaxation, decreasing anxiety, and modulating pain perception. This study aimed to determine the effect of deep breathing relaxation techniques combined with classical music therapy on postoperative pain among mothers following cesarean section at RSIA BROS. Method: This study employed a quantitative quasi-experimental design using a non-equivalent control group design. A total of 60 postpartum mothers who underwent cesarean section were recruited using an accidental sampling technique. Result: Pain intensity was assessed before and after the intervention, and the data were analyzed to determine the effectiveness of the intervention. The findings demonstrated a statistically significant effect of deep breathing relaxation techniques combined with classical music therapy on postoperative pain among mothers following cesarean section, with a p-value of 0.000 (p < 0.05). Conclusion: the combination of deep breathing relaxation techniques and classical music therapy effectively reduced postoperative pain among mothers after cesarean section.