Serotonin, a pivotal neurotransmitter in the central nervous system (CNS), plays a crucial role in mood disorders, neurodegenerative diseases, and migraine. Its dysfunction is closely linked to depression and anxiety, with selective serotonin reuptake inhibitors (SSRIs) widely used as antidepressants. In neurodegenerative diseases , reduced serotonergic activity correlates with cognitive decline and disease progression. Serotonin's neuroprotective effects, including modulation of neuroinflammation and oxidative stress, are essential in these conditions. In migraine, altered serotonin levels influence vascular tone and pain perception, with serotonin receptor agonists effectively aborting attacks. Understanding serotonin's multifaceted roles can lead to better therapeutic strategies for these CNS diseases.