Marine ecosystems are a relatively unexplored and abundant source of natural bioactive chemicals with enormous promise for biological uses. Marine-derived compounds have recently received a lot of interest in their potential involvement in the diagnosis and treatment of neurological and neurodegenerative diseases. This chapter investigates the prospective value of marine bioactives as innovative diagnostic tools, emphasizing their specificity, sensitivity, and flexibility to evolving diagnostic demands. As the global prevalence of neurological conditions develops, there is a greater desire for more accurate, early-stage, and even tailored diagnostic treatments. Marine natural materials have unique structural and functional features that can help overcome this diagnostic gap. The chapter underlines the necessity of further exploration and multidisciplinary study in unlocking the therapeutic and diagnostic potential of marine-derived chemicals. These studies may eventually lead to advances in diagnosing and controlling hitherto untreatable diseases, ushering in a new era in neuromedicine.