Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract with a multifactorial etiology. Given the limitations and adverse effects of current therapies, there is a need for novel therapeutic approaches. Drug repurposing presents a promising opportunity to utilize medications with known safety and pharmacological profiles for alternative colitis treatment. Emerging evidence suggests the renin-angiotensin system (RAS) plays a significant role in the colitis pathophysiology. Angiotensin-converting enzyme (ACE) inhibitors may offer therapeutic potential by modulating pro-inflammatory cytokines and reducing oxidative stress. This study aims to evaluate the efficacy of lisinopril (LIS) in a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis model in Wistar rats. Colitis was induced in Wistar rats via a single intracolonic TNBS dose (100 mg/kg). Treatment groups received oral interventions for 5 days: 5-aminosalicylic acid (5-ASA; 25.5 mg/kg), LIS (10 mg/kg), or LIS (20 mg/kg). Efficacy was evaluated using the disease activity score rate (DASR), colon/body weight ratio (CBWR), and colon length, diameter, and pH. Colonic tissue was analyzed macroscopically and histopathologically. Inflammatory biomarkers interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), oxidative stress markers glutathione (GSH), and malondialdehyde (MDA), as well as C-reactive protein (CRP) and complete blood count (CBC), were measured. LIS significantly reduced colitis severity, decreasing DASR and CBWR, while restoring colon dimensions and pH. LIS showed potent anti-colitic effects by suppressing TNF-alpha and IL-6 levels, reducing MDA, and increasing GSH. LIS restored RBC and WBC levels while normalizing CRP and hemoglobin levels. Histopathological and macroscopic analyses confirmed colonic protection with minimal detrimental effects on the stomach and liver. LIS, particularly at 20 mg/kg, exhibited dose-dependent anti-inflammatory, antioxidant, and tissue-protective effects, showing promise as a therapeutic agent for colitis treatment.