Exosomes, nanoscale extracellular vesicles released by several cell types, have become essential facilitators of intercellular communication in both physiological and pathological contexts. MicroRNAs (miRNAs) are prominent components of their varied payload, significantly affecting gene expression and cellular processes. In cancer, exosomal miRNAs serve dual functions as either oncogenic or tumor-suppressive factors, influencing cancer cell proliferation, invasion, metastasis, and therapeutic resistance. This chapter comprehensively examines the biogenesis and molecular processes that support exosomal miRNA-mediated signaling pathways. The potential of exosomal miRNAs as biomarkers for early cancer diagnosis and prognosis is examined, alongside the formulation of treatment techniques that utilize their regulatory roles. The chapter finishes by addressing the obstacles and future prospects of using exosomal miRNAs in cancer therapy, emphasizing their scalability, delivery mechanisms, and translational promise in precision medicine.