Cervical spondylosis represents a common age-related degenerative disorder of the cervical spine that frequently results in spinal canal narrowing and varying degrees of neurological impairment. The severity of cervical canal stenosis, as identified through magnetic resonance imaging (MRI), is thought to influence the extent of neck-related functional disability; however, the strength and consistency of this association remain debated. This review explores the relationship between the radiological severity of cervical spinal canal stenosis and the Neck Disability Index (NDI) in patients with cervical spondylosis, emphasizing MRI-based assessment parameters. An analysis of relevant literature indicates that greater canal narrowing is generally associated with higher NDI scores, reflecting increased functional limitation and pain. Most studies have shown a moderate to strong correlation between MRI-graded stenosis and disability levels, although differences in grading criteria, measurement indices, and study populations contribute to some variability in findings. Notably, parameters such as the Torg–Pavlov ratio, cord compression ratio, and the number of affected segments appear to serve as more reliable indicators of clinical severity than single-level diameter assessments. Collectively, the evidence suggests that MRI evaluation offers an objective tool to estimate disease burden and to predict patient disability, supporting its integration into clinical assessment and treatment planning. Standardization of imaging criteria and large-scale longitudinal studies are required to strengthen the prognostic accuracy and clinical applicability of these correlations.