MicroRNAs (miRNAs/miRs) serve important roles in the chemotherapeutic effect of anticancer drugs. To investigate the roles of miRNAs in cisplatin-induced suppression of lung adenocarcinoma cell proliferation, A549 cells were treated with different concentrations of cisplatin. An MTT assay demonstrated that cisplatin inhibited A549 cell proliferation in a dose-dependent manner. Cisplatin induced cell apoptosis and inhibited cell migration by increasing the levels of miR-93, miR-26a and miR-26b. Furthermore, as an upstream factor, miR-93 was proposed to regulate cyclin D2 expression in miR-93-transfected A549 cells. Cisplatin also induced Bcl-2-associated X protein expression, and decreased that of Bcl-2 and c-Myc in lung adenocarcinoma cells. In vivo analysis further supported that cisplatin inhibited lung adenocarcinoma cell growth by regulating cyclin D2 and miR-93 expression. In conclusion, our findings demonstrated that cisplatin could effectively inhibit lung adenocarcinoma cell proliferation by decreasing cyclin D2 expression via miR-93.