Background: Cesarean section associated with persistent postoperative discomfort is a well-known side effect of this operation. Benson's Muscle Relaxation Technique is an effective complementary and non-pharmacological technique used to reduce incisional pain and stress levels. Aim: To evaluate the effect of Benson relaxation therapy on post-operative pain and stress among nulliparous women undergoing cesarean section. Design: A quasi-experimental design was used to achieve the aim of this study. Setting: The study was conducted in the obstetrics and gynecology department affiliated to Mansoura University Hospital. Subject: Non-probability purposive sampling technique was used to select a sample of 100 post-operative women undergoing cesarean section who were randomly assigned into two groups, 50 for each the study and control groups. Four tools were used: (I) a structured interview questionnaire, (II) a numerical pain rating scale, and (III) Perceived Stress Scale-10 (PSS-10). Results: The present study findings demonstrated that there was a statistically significant difference between mean pretest and posttest scores in the study group regarding pain level at the p<0.05 level. Furthermore, there were highly statistically significant differences in scores in the study group compared to the control group pain (P<0.05). Highly statistically significant differences were found between both groups as regards stress levels. Conclusion: Benson relaxation therapy was found to be useful in minimizing pain and stress levels among nulliparous women undergoing cesarean section. Recommendations: Benson relaxation therapy is recommended alongside treatment for nulliparous women undergoing cesarean section to reduce pain and stress.