Abstract Objectives Hypertension is the number one risk factor and primary contributor of cardiovascular diseases. Caesalpinia benthamiana is a valuable medicinal plant with unvalidated anti-hypertensive activity. This study was carried out to explore the antihypertensive effect of C. benthamiana on uninephrectomized hypertensive rats. Methods Fifty rats were grouped into five groups, each containing 10 animals: Group A-normal control (normotensive); B-uninephrectomized control; C-uninephrectomized treated with 50 mg/kg C. benthamiana extract; D-uninephrectomized treated with 100 mg/kg C. benthamiana; and E- uninephrectomized treated with 10 mg/kg of Lisinopril. Results Significant increases were observed in systolic, diastolic and mean blood pressure of uninephrectomized control rats. Furthermore, markers of oxidative stress (malondialdehyde, hydrogen peroxide, protein carbonyl, myeloperoxidase and the advanced oxidative protein products) increased significantly while antioxidant status (reduced glutathione, glutathione peroxidase, glutathione S-transferase and superoxide dismutase), reduced significantly in uninephrectomized hypertensive rats. Histopathology revealed thrombosis and occlusion of coronary vessels in the heart, and congestion in the kidney. However, the observed high blood pressure parameters were remarkably normalized together with reduction in markers of oxidative stress and improvement in antioxidant defence system of uninephrectomized hypertensive rats treated with C. benthamiana extract similar to normotensive rats. Conclusions C. benthamiana extract exhibited antihypertensive action, strong antioxidant ability, attenuated oxidative stress-mediated hypertension and lessened the development of cardiac and renal damage associated with hypertension induced by uninephrectomy and high dietary intake of salt. Together, C. benthamiana extract might be useful in the management of hypertension due to volume overload in the cardiovascular system.