microRNAs (miRNAs) serve as post-translational modulators for numerous genes, acting not only as indicators of cancer onset and progression but also as markers for the efficacy of anticancer treatments. Their ability to adjust cellular responses to treatments positions them as valuable targets in the battle against various diseases. With the advancement of technologies, researchers have developed numerous strategies to explore the optimal pathways for miRNA delivery to diseased cells, including the use of synthetic miRNA analogs, miRNA-encoding DNA plasmids, and compounds that modify miRNA expression through epigenetic mechanisms. Evidence from animal studies and preclinical research in both solid tumors and blood cancers has supported the efficacy of microRNA-based treatment approaches. However, challenges persist in the clinical application of miRNAs, such as creating stable nanoformulations, selecting appropriate delivery methods, and managing biodistribution. This chapter aims to outline the process of miRNA biogenesis and their use in treating human diseases.