Recent advancements in microRNAs (miRNAs) research have revealed their key roles in both normal physiological processes and pathological conditions, leading to potential applications in diagnostics and therapeutics. However, the path forward is fraught with several scientific and technical challenges. This review article briefly explores the milestones of the discovery, biogenesis, functions, and application for clinical diagnostic and therapeutic strategies of miRNAs. The potential challenges and future directions are also discussed to fully harness their capabilities.