Background: High-risk pregnancy refers to a situation in which the pregnancy is complicated by various factors. These factors can lead to increased psychological stress for the pregnant woman as well as experiencing depression and anxiety. Among the various relaxation methods, Benson's relaxation used for reducing anxiety by influencing both mental and physical conditions, It is considered to be one of the simplest to administer and learn. Aim: To evaluate the impact of Benson's relaxation therapy on anxiety levels in antenatal mothers with high-risk pregnancies. Design: The present study employed a quasi-experimental research design. Setting: The study was performed at the obstetric and gynecologic department in Damanhour National Medical Institute. Subjects: A sample of 80 pregnant women with high-risk pregnancies was conveniently selected. Tools: Data collection utilized four tools. Tool one: Structured interview schedule for socio-demographic and reproductive history. Tool Two: The Groningen Sleep Quality Scale (GSQS). Tool Three: Perinatal Anxiety Screening Scale (PASS) Results: The finding of this study reveals a highly statistically significant distinction among the studied groups concerning the maintenance of physiological parameters (respiratory rate, blood pressure, and pulse rate) inside normal ranges (P≤ 0.05).. Furthermore, the study group demonstrated a significant enhancement in sleep quality, with the percentage of subjects experiencing good quality of sleep increasing from 12.5% to 80% post-intervention, while the control group maintained a high mean quality of sleep even after the fifth day of intervention. Additionally, all participants in the study group no longer had severe anxiety symptoms, in contrast to 77.5% of the control group. Moreover, there was a notable rise in the percentage of study group participants with asymptomatic anxiety, rising from 15% before the intervention to 75% after. This difference was highly statistically significant among both groups (p ≤ 0.05). Conclusion: The outcomes of this study performed that Benson relaxation therapy (BRT) positively an impact on stress reduction and enhance sleep quality in high-risk pregnant women. Furthermore, BRT has shown significant effectiveness in regulating physiological indicators, like respiratory rate, blood pressure, and pulse rate to optimal levels. Recommendations: Benson relaxation method is an affordable, highly efficient, and user-friendly therapy for women experiencing high-risk pregnancies. Therefore, it is recommended that the nursing team incorporate these techniques into the care plan for this particular group of expectant mothers.