cMet is critical in regulating inflammation, apoptosis, and fibrosis. We investigated the correlation between urinary cMet (ucMet) levels and clinical parameters in immunoglobulin A nephropathy (IgAN). We also examined the effects of cMet agonistic antibody (cMet Ab) in an in vitro IgAN model. Patients diagnosed with IgAN (n = 179) were divided into groups 1, 2, and 3, representing undetectable, below median, and above median levels of ucMet/creatinine (Cr). Stained kidney samples were graded according to cMet intensity. Primary-cultured human mesangial cells were stimulated with recombinant tumor necrosis factor (TNF)-α and treated with cMet Ab. ucMet/Cr levels were positively correlated with proteinuria (P < 0.001). During follow-up, patients in group 3 showed a significantly lower probability of complete remission (CR) than those in groups 1 and 2. The result remained significant after adjusting for blood pressure, estimated glomerular filtration rate, and proteinuria, which influence clinical prognosis (HR 0.61, 95% CI 0.37-0.98, P = 0.042). Particularly, in patients with proteinuria ≥ 1 g/day, as ucMet/Cr levels increased, the probability of CR decreased (HR 0.24, 95% CI 0.12-0.46, P < 0.001). ucMet/Cr levels were associated with glomerular cMet expression. After TNF-α treatment, the proliferation of mesangial cells and increased interleukin-8 and intercellular adhesion molecule-1 expression were markedly reduced by cMet Ab in vitro. ucMet/Cr levels were significantly correlated with proteinuria, glomerular cMet expression, and the probability of CR. Inflammation and proliferation of mesangial cells were alleviated by cMet Ab treatment. ucMet could be clinically significant in treating IgAN.