Parkinson’s disease (PD) is a neurodegenerative disorder characterized by high clinical heterogeneity. Its diagnosis primarily relies on clinical symptoms and limited imaging evidence, making early diagnosis and treatment challenging. Functional near-infrared spectroscopy (fNIRS) is an emerging optical imaging technique that can indirectly reflect changes in brain metabolic activity. Currently, patients with PD exhibit enhanced activation of the frontal lobe in most studies involving motor tasks based on fNIRS, demonstrating the compensatory role of the frontal lobe in PD. In recent years, the scope of fNIRS research has gradually expanded to include non-motor symptoms and brain connectivity analysis in PD, a field that currently has limited research but offers significant potential for further study. This review focuses on the application of fNIRS in the clinical symptoms and rehabilitation treatment of PD, aiming to provide assistance for future research on PD.