The most annoying complaints from women after Caesarean sections are pain, sleep difficulties and a restriction on physical activity. A possible treatment for these complaints is Jacobson's progressive muscle relaxation (JPRT). This study aimed to evaluate the effect of Jacobson's relaxation technique on post cesarean section pain, sleep quality and physical activities. Design: a randomized controlled clinical trial. Methods: A convenience sample of 120 women undergoing CS from the maternity facility at Zagazig University Hospitals, Sharkia Governorate, Egypt, was selected, with 60 being placed in the intervention group and 60 being recruited for the control group. Tools: Structured interview schedule, Visual Analogue Scale (VAS), Physical Activities Limitation Questionnaire, and Groningen Sleep Quality Scale were the four instruments utilized to gather the data. Results: Jacobson's relaxation technique greatly reduced level of pain among intervention group compared to the control group. On the first day, 48.3% of participants in the intervention group had uncontrolled severe pain, compared to 55.0% in the control group; on the second day, it was 21.7% vs. 46.7%; and on the third day, it was 15.0% vs. 45.0%. These variations have statistically significant differences. The mean score after JPRT intervention was 10.5±2 versus 11.4±1.4 on the second day and on the third day was 6.6±3.8 versus 11.3±1.3, respectively, with a highly statistically significant difference between them. (p=0.001). A statistically significant difference in the physical activity limitation score among the intervention group (P=0.0001), with the severe physical activity limitation considerably absent from the entire intervention group on the third day following the intervention. Conclusion: It was clear that Jacobson's relaxation technique is a helpful and secure strategy that reduces pain intensity, enhances sleep quality and lower physical activities limitation in post-cesarean mothers. Recommendation: incorporating Jacobson's relaxation method into the nursing care program for women who have undergone caesarean sections.