Fibroblast Growth Factor 9 (FGF9) is an important member of the fibroblast growth factor family, which regulates multiple cellular processes including proliferation, differentiation, apoptosis, and migration. It has been demonstrated to play significant roles in tissue and organ development, energy metabolism, and the progression of tumors such as lung and liver cancers. However, research on its effects on the nervous system remains limited. This review focuses on the impact of FGF9 on the development and function of the nervous system, encompassing neuronal protection, astrocyte differentiation, neural regulation, and the growth of nervous system tumors. We also explore the underlying mechanisms, aiming to provide new targets for the treatment and prevention of related diseases.