MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression at the posttranscriptional level and play a critical role in maintaining cellular homeostasis. Dysregulation of miRNAs is a hallmark of many cancers, where they function either as oncogenes (oncomiRs) or tumor suppressors. This review highlights the intricate relationship between miRNAs and cell cycle regulation in cancer progression. OncomiRs such as miR-21, miR-155, and the miR-17-92 cluster are frequently overexpressed in cancers and promote tumor growth by targeting key tumor-suppressor genes. In contrast, tumor-suppressor miRNAs like let-7, miR-34a, and the miR-200 family are often downregulated, leading to uncontrolled proliferation and metastasis. Moreover, aberrant miRNA expression contributes to chemoresistance by modulating apoptosis and drug response pathways. The dual role of miRNAs in cancer pathogenesis underscores their potential as diagnostic biomarkers and therapeutic targets. Advances in miRNA-based therapies, including mimics and inhibitors, offer promising avenues for cancer treatment. This review provides a comprehensive overview of miRNA-mediated cell cycle control and its implications in oncogenesis, paving the way for future research and clinical applications in cancer management.