Background/Objectives:Nelumbo nucifera Gaertn. (lotus) seeds have traditionally been used to treat hypertension, though their mechanisms remain unclear. This study investigated the antihypertensive effects of lotus seed extract (LSE) and its mechanisms in rats with N(ω)-nitro-L-arginine methyl ester (L-NAME)-induced hypertension. Methods: Male Sprague Dawley rats received L-NAME (40 mg/kg/day) in drinking water and were treated orally with LSE (5, 10, or 100 mg/kg/day), captopril (5 mg/kg/day), or a combination of LSE and captopril (2.5 mg/kg/day each) for 5 weeks. Hemodynamic parameters and histological changes in the left ventricle and aorta were assessed. Mechanistic studies included measurements of plasma nitric oxide (NO) metabolites, malondialdehyde (MDA), superoxide dismutase (SOD) activity, angiotensin II (Ang II), angiotensin-converting enzyme (ACE) activity, and protein expression via western blot. Results: L-NAME elevated systolic blood pressure and induced cardiovascular remodeling, oxidative stress, and renin-angiotensin system activation. LSE treatment reduced blood pressure, improved antioxidant status, increased NO bioavailability, and downregulated gp91(phox) and AT(1)R expression. The combination of low-dose LSE and captopril produced stronger effects than LSE alone, with efficacy comparable to captopril. Conclusions: These findings suggest that LSE exerts antihypertensive effects via antioxidant activity and inhibition of the renin-angiotensin system, supporting its potential as an adjunct therapy for hypertension.