Hydrogen sulfide (H2S) is a bioactive gas with potential neuroprotective properties. This study explores the therapeutic efficacy of chondroitin sulfate (CS) in a Parkinson's disease (PD) mouse model by evaluating its impact on behavior, gut microbiota composition, substantia nigra (SN) pathology, oxidative stress, and inflammation. Behavioral tests indicate that CS improves cognitive function and learning abilities in PD mice. Gut microbiota analysis and fecal H2S content measurement reveal that CS fosters the growth of Desulfovibrio and boosts H2S production, respectively. Further examination shows that CS treatment enhances antioxidant defenses, reduces inducible nitric oxide synthase (iNOS)-mediated inflammation, and alleviates PD-related pathology and α-synuclein overexpression in the SN. These findings suggest that CS modulates the gut microbiota and its metabolic product, H2S, potentially improving PD symptoms through the gut-brain axis.