Mirabegron is a beta 3-adrenoceptor agonist that can help with incontinence, dysuria, and bladder overactivity. It alleviates the symptoms of prostate enlargement and urinary tract infections (UTIs) in the elderly. We aimed to explore Mirabegron’s antimicrobial and immune-boosting properties, trying to benefit people suffering from urinary tract infections and having an overactive bladder. Mirabegron’s putative antibacterial activity was investigated using the well diffusion method (In Vitro). Infected rats were treated with mirabegron (10 mg/kg, oral) and used for evaluation of immunomodulatory actions (In Vivo). We tested the antibacterial activity in vitro against numerous bacterial strains, including Escherichia coli (E. coli). The phagocytic activity and survival of peritoneal macrophages were examined. Also, serum levels of immunoglobulin G (IgG), immunoglobulin M (IgM), and interferon-γ (INF-γ) were estimated in E. coli-infected rats. We found that mirabegron exhibited significant antibacterial activity, particularly against E. coli. Phagocytic activity increased notably in vivo, indicating an improved innate immune response. Mirabegron also demonstrated a substantial rise in immunoglobulin and cytokine levels, enhancing acquired immunity. According to our findings, in vitro and in vivo tests of mirabegron revealed possible antibacterial activity as well as immunomodulatory properties. Mirabegron could alleviate symptomatic UTIs.