Background: The caesarean birth rate has risen dramatically globally, including in Egypt. Cesarean section is one of the commonly performed surgical procedures in the field of obstetrics. This study aimed to compare the analgesic efficacy of intraoperative intravenous aqueous diclofenac sodium with transversus abdominis plane block in caesarean section under spinal anaesthesia as part of multimodal analgesia regimen. Methods: This randomized comparative study was conducted on sixty women who underwent cesarean section. The patients were divided into two groups: First group (A): underwent TAP block only and second group (B): underwent TAP block and intravenous diclofenac sodium. Results: Group B had a statistically significantly longer time to first rescue analgesic compared to Group A (p < 0.001). Mean dose of total analgesic consumption in first 24 h post-surgery was found lesser in Group B compared to that in Group A, which was statistically significant (P < 0.001). Group B had a significantly higher satisfaction score compared to Group A (p < 0.001). Conclusion: The results demonstrated a statistically significant improvement in pain management for patients in the group receiving both TAP block and intravenous diclofenac sodium compared to those receiving only the TAP block. These findings suggest that the addition of intravenous diclofenac sodium to the TAP block enhances the analgesic efficacy and patient satisfaction, making it a superior option for post-cesarean section pain management within a multimodal analgesia regimen.