Nanoparticle-based biomarkers have emerged as a transformative tool for the diagnosis and monitoring of neurological disorders, offering unparalleled sensitivity and specificity. This chapter explores the application of diverse nanoparticles, including gold nanoparticles, quantum dots, and magnetic nanoparticles, in detecting biomarkers for diseases such as Alzheimer’s, Parkinson’s, multiple sclerosis, and stroke. Nanoparticles’ unique properties, such as their ability to cross the blood-brain barrier and their tunable optical and magnetic characteristics, enable precise detection of pathological proteins like amyloid-beta, tau, and alpha-synuclein. Recent advances demonstrate the potential of these nanoparticles to revolutionize early diagnosis, track disease progression, and monitor therapeutic responses. Despite promising results, challenges remain in terms of biocompatibility, safety, and regulatory approval. This chapter provides a comprehensive overview of current research, highlights the advantages of nanoparticle-based biomarkers over traditional methods, and discusses the future prospects and potential impacts on clinical practice. By addressing these key aspects, we aim to underscore the critical role of nanoparticle-based biomarkers in advancing neurological disorder diagnostics and therapy.