Prion diseases are rapidly progressive and fatal neurodegenerative disorders caused by misfolded prion proteins. Accurate and early diagnosis is essential to distinguish these conditions from treatable dementias and to prevent iatrogenic transmission. While definitive confirmation still depends on postmortem neuropathological techniques such as immunohistochemistry and western blot, recent advances have significantly improved antemortem diagnostic capabilities. The antemortem diagnosis combines clinical evaluation, neuroimaging, electroencephalography, and cerebrospinal fluid biomarkers. The development of real-time quaking-induced conversion (RT-QuIC) has enhanced the detection of misfolded prion proteins with high specificity, complementing existing diagnostic methods. Although advancements in biomarkers and diagnostic methodologies have improved the early detection of prion diseases, challenges remain. Continued research is crucial for enhancing early identification, tracking disease progression, optimizing patient management, and further elucidating disease pathogenesis.