Background: Preeclampsia (PE) is the most prevalent serious pregnancy disorder, complicating 2% to 8% of all pregnancies worldwide, and remains the leading cause of maternal and fetal morbidity and mortality. The application of appropriate management is crucial to avoid the associated complication. Aim: This study aimed to evaluate the effect of progressive muscle relaxation technique (PMRT) on maternal-fetal physiological parameters and stress among preeclamptic women. Methods: A quasi-experimental research design was used. A convenient sample of 80 pregnant women with mild preeclampsia was recruited from El Shatby Maternity University Hospital in Alexandria governorate. Four tools of data collection were used: (1) basic data structured interview schedule (2) Maternal physiological parameters assessment sheet (3) Non-stress test recording strip (the cardiotocograph) (4) Cohen's perceived stress scale short version (PSS-10). Results: The results showed a significant decline in systolic, diastolic blood pressure, pulse rate, and proteinuria at 3 and 7 days after practicing progressive muscle relaxation technique among the study group. Also, a statistically significant difference was observed between intervention and control groups in terms of baseline fetal heart rate (0.026), the number of fetal movements (0.005) acceleration (0.005), and reactivity (0.02) based on the non-stress test. Regarding the stress level, PMRT improved stress level in the study group on the 3rd and 7th days following the intervention. Conclusion: PMRT has been proven to be an effective, simple, and inexpensive non-pharmacological nursing intervention that enhances maternal and fetal physiological parameters and reduces the stress level in preeclamptic women. Recommendation: Maternity nurses should integrate PMRT as non - a pharmacological approaches in their nursing care of pregnant women with preeclampsia.