Background <p>Idiopathic membranous nephropathy (IMN) is a leading cause of adult nephrotic syndrome, yet the impact of renal arteriolosclerosis in IMN remains understudied. The primary objective of this study was to investigate the prognostic impact of renal arteriolosclerosis on patients with IMN.</p> Methods <p>In this single-center retrospective cohort study, patients with biopsy-proven IMN diagnosed between June 2013 and March 2021 were stratified into two groups based on the presence or absence of renal arteriolosclerosis. Clinical and pathological data were analyzed. Kaplan–Meier survival analysis and multivariable Cox proportional hazards models were employed to evaluate the association between arteriolosclerosis and a composite kidney endpoint.</p> Results <p>Among 191 enrolled patients, 137 (72%) exhibited renal arteriolosclerosis. This group presented with significantly higher blood pressure, more severe glomerulosclerosis and interstitial lesions, and lower baseline eGFR (all <i>P</i> &lt; 0.05). Kaplan–Meier analysis revealed significantly poorer renal survival in patients with renal arteriolosclerosis. In multiple regression equation analysis, after adjustment for confounding variables including age, hypertension, and baseline renal function, arteriolosclerosis remained an independent risk factor for adverse renal outcomes (adjusted HR = 8.77, 95%CI = 1.06–72.86, <i>P</i> &lt; 0.05).</p> Conclusions <p>Arteriosclerosis serves as an independent predictor of adverse outcomes in IMN patients, emphasizing the importance of targeted therapeutic intervention in clinical practice.</p>