Background: Recent research highlights the glymphatic system’s role in clearing waste from the central nervous system. Its dysfunction is linked to neurodegenerative diseases like Alzheimer’s and Parkinson’s, but its impact on multiple sclerosis (MS) remains unclear. This retrospective study examines glymphatic function in MS and its link to clinical disability using MRI. Methods: The study included 18 patients diagnosed with MS, comprising 3 with primary progressive MS and 15 with secondary progressive MS, along with 7 healthy control participants. All subjects underwent neurological evaluations and MRI assessments, which included high-resolution T1, T2, and diffusion-weighted imaging. Statistical comparisons between the groups were conducted using a two-sample t-test. Results: MS patients exhibited a reduced diffusion along the perivascular space index (DTI-ALPS) compared to healthy controls. Patients with primary progressive MS demonstrated lower DTI-ALPS values than those with secondary progressive MS. Lower DTI-ALPS was associated with a higher Expanded Disability Status Scale (EDSS) score, indicating a correlation between glymphatic system dysfunction and greater clinical disability in MS. Conclusions: The study suggests that glymphatic system dysfunction is present in MS and is inversely associated with the severity of disability. This impairment may contribute to the disease’s pathological mechanisms.