Exosomes are 40–100 nm vesicles released by cells into the extracellular space, containing various molecules including miRNAs. These vesicles can transfer miRNAs to neighboring or distant cells, modulating recipient cell functions. Exosomal miRNAs play roles in disease progression, angiogenesis, and metastasis. The sorting of miRNAs into exosomes is an active process, with specific miRNAs preferentially entering exosomes. The mechanisms of miRNA sorting include nSMase2-dependent pathways, miRNA motif and sumoylated hnRNPs-dependent pathways, 3'-end sequence-dependent pathways, and miRISC-related pathways. Exosomal miRNAs have potential applications in clinical settings as biomarkers for disease diagnosis and monitoring. They can also be used in gene therapy by delivering exogenous miRNAs or siRNAs via exosomes. However, challenges remain in understanding the precise mechanisms of exosomal miRNA sorting and function, as well as in developing methods for efficient isolation and quantification of exosomal miRNAs. Further research is needed to fully explore the therapeutic potential of exosomes and their miRNAs.Exosomes are 40–100 nm vesicles released by cells into the extracellular space, containing various molecules including miRNAs. These vesicles can transfer miRNAs to neighboring or distant cells, modulating recipient cell functions. Exosomal miRNAs play roles in disease progression, angiogenesis, and metastasis. The sorting of miRNAs into exosomes is an active process, with specific miRNAs preferentially entering exosomes. The mechanisms of miRNA sorting include nSMase2-dependent pathways, miRNA motif and sumoylated hnRNPs-dependent pathways, 3'-end sequence-dependent pathways, and miRISC-related pathways. Exosomal miRNAs have potential applications in clinical settings as biomarkers for disease diagnosis and monitoring. They can also be used in gene therapy by delivering exogenous miRNAs or siRNAs via exosomes. However, challenges remain in understanding the precise mechanisms of exosomal miRNA sorting and function, as well as in developing methods for efficient isolation and quantification of exosomal miRNAs. Further research is needed to fully explore the therapeutic potential of exosomes and their miRNAs.