Background: Lower urinary tract symptoms (LUTS) due to prostate hyperplasia are the most frequent urological symptoms in elderly men. Current pharmacological treatments for LUTS and benign prostatic hyperplasia (BPH) are widely used in clinical practice; however, adverse effects associated with these drugs have been reported for sexual dysfunction and orthostatic hypotension. Prunella vulgaris (PV) is a medicinal herb that has a long history of use. This study aimed to address this gap by investigating the relaxant activity of PV extract (PVE) on rat prostate smooth muscle ex vivo and evaluating intravesical cystometry for its potential. Methods and Results: Ten male Sprague Dawley (SD) rats were used to study the relaxant efficacy of PVE and its constituents in isometric contraction ex vivo. Thirty-six SD rats were randomly assigned to six groups of six animals (n = 6) and administered testosterone propionate (TP; 3 mg/kg) daily for 4 weeks to induce BPH. Groups of BPH rats were treated with or without PVE (30, 60, or 90 mg/kg) via oral gavage. At the end of the experiments, the animals were subjected to intravesical pressure under urethane anesthesia. After successful cystometric recording, rats were euthanized with carbon dioxide. Prostate and bladder tissues were harvested and processed for histological and biochemical analysis. The results demonstrated that PVE exerted relaxant effects on prostatic smooth muscle in a concentration-dependent manner, mediated by nitric oxide and potassium channels, without antagonizing adrenergic receptors. Additionally, intravesical cystometry in SD rats treated with oral gavage of PVE for 4 weeks showed a significant improvement in voiding abnormalities. Conclusions: These findings suggest the potential of PV and its compounds as a therapeutic strategy to improve LUTS associated with BPH.