Objective To investigate the effects of early mobilization within 48 h of injury on motor function and walking ability in patients with incomplete cervical spinal cord injury (SCI). Design A retrospective observational study. Setting Intensive care unit or high care unit of a university hospital emergency center. Participants Of 224 patients with SCI having American Spinal Injury Association impairment scale grades C and D, 158 consecutive patients hospitalized for at least 3 weeks after injury were included. Interventions Patients were categorized into two groups: an early mobilization group in which patients were mobilized within 48 h of injury and a delayed mobilization group in which they were mobilized after 48 h of injury. Outcome measures The upper extremity motor score (UEMS), lower extremity motor score (LEMS), and Walking Index for Spinal Cord Injury II (WISCI II) were compared using propensity score matching analysis. Results Of the 158 patients who met the eligibility criteria, 32 were matched between the groups. There was a significant difference in the change in LEMS from the initial assessment to the assessment 2 weeks postoperatively in the early mobilization group (median 9 points vs. 3 points, p < 0.05). There were no significant differences in UEMS or WISCI II. Conclusion Early mobilization within 48 h may improve lower extremity motor function in patients with acute incomplete cervical SCI.