Bladder cancer (BLCA) is an aggressive malignancy characterized by limited therapeutic options and a poor prognosis. Research has indicated that abnormally expressed miRNAs play a significant role in the pathogenesis of BLCA, although the specific mechanisms remain unclear. MiR-125b plays a tumor suppressor role in a variety of cancers and affects the biological processes of cancer cells such as proliferation, invasion, migration and apoptosis by regulating different signaling pathways. Elucidation of the molecular mechanisms underlying miR-125b may provide clinical therapeutic strategies for bladder cancer. Here, miR-125b was downregulated whereas its targets IL-6R and STAT3 were upregulated in BLCA, as evidenced by bioinformatics analysis. Kaplan-Meier analysis confirmed that miR-125b serves as an independent prognostic factor linked to overall survival (OS) in patients with bladder cancer. Furthermore, overexpression of miR-125b significantly inhibited BLCA cell proliferation, migration, and invasion, while promoting apoptosis, as evidenced by an increased Bax/Bcl-2 ratio and activated cleaved caspase-3. Further investigations demonstrated that miR-125b directly targets and downregulates both IL-6R and STAT3. In a xenograft model, miR-125b overexpression effectively inhibited tumor growth in bladder cancer by blocking IL-6/IL-6R and STAT3 signaling pathways. Collectively, these findings broaden our understanding of the mechanism by which miR-125b acting as a BLCA suppressor in apoptotic regulation by targeting the IL-6/IL-6R/STAT3 signaling pathway, providing novel insights regarding the design of novel miRNA based therapeutic strategies against BLCA.Copyright © 2025 Elsevier Ltd. All rights reserved.