The present investigation demonstrated that regulation of microRNA (miR)-125b affected the apoptosis of human non-small cell lung cancer (NSCLC) through targeting of the PI3K/Akt and Wnt/β-catenin signaling pathways. The expression of miR-125b was assessed in patients with NSCLC, which demonstrated that miR-125b expression in NSCLC tissue was higher than that in para-carcinoma tissue. Furthermore, survival analysis of patients with NSCLC over 3 years indicated that the overall survival (OS) and disease-free survival (DFS) rates of patients with low miR-125b expression were higher than those of patients with high miR-125b expression. Proliferation and apoptosis assays were subsequently conducted in the human NSCLC cell line A549 using MTT assay and Annexin V-FITC/PI kits, respectively. Caspase-3 activity ELISA and western blot analysis were also used to assess caspase-3 activity and the protein expression of Bax, Akt, phosphorylated (p)-Akt, p-GSK3β, Wnt and β-catenin. It was observed that downregulation of miR-125b inhibited the proliferation and induced the apoptosis of A549 cells. Downregulation of miR-125b also suppressed the protein expression of p-Akt, Wnt and β-catenin, and increased caspase-3 activity and Bax protein expression in A549 cells. In addition, downregulation of miR-125b combined with the PI3K inhibitor LY294002 enhanced cell growth inhibition, suppression of p-GSK3β, Wnt and β-catenin protein expression and promotion of caspase-3 activity in A549 cells. These results revealed that the downregulation of miR-125b regulates apoptosis in human NSCLC through the suppression of the PI3K/Akt/GSK3β and Wnt/β-catenin signaling pathways.