MicroRNAs (miRNAs) have emerged as pivotal regulators in cancer biology, influencing tumorigenesis, progression, and resistance to therapy. Their ability to modulate multiple oncogenic and tumor-suppressive pathways positions them as promising therapeutic tools or targets. This review examines the dual role of miRNAs in solid and hematological malignancies, starting from their dysregulation in various cancer types. Therapeutic approaches, including miRNA replacement and inhibition strategies, are discussed alongside innovative delivery systems such as lipid nanoparticles and exosomes. Despite their transformative potential, challenges persist, including off-target effects, immune activation, and delivery inefficiencies. Recent clinical trials demonstrate both progress and hurdles, underscoring the need for advanced strategies to optimize specificity and minimize toxicity. This review provides an updated comprehensive overview of the current landscape of miRNA-based therapies under early clinical investigation and explores future directions for integrating these approaches into precision oncology.