BACKGROUND: Literature evaluating frailty in traumatic spinal cord injury (tSCI) is limited. OBJECTIVE: To evaluate the prognostic significance of baseline frailty status in tSCI. METHODS: Patients with tSCI were identified in the National Inpatient Sample from 2015 to 2018 and stratified according to frailty status, which was quantified using the 11-point modified frailty index (mFI). RESULTS: Among 8825 operatively managed patients with tSCI identified (mean age 57.9 years, 27.6% female), 3125 (35.4%) were robust (mFI = 0), 2530 (28.7%) were prefrail (mFI = 1), 1670 (18.9%) were frail (mFI = 2), and 1500 (17.0%) were severely frail (mFI ≥ 3). One thousand four-hundred forty-five patients (16.4%) were routinely discharged (to home), and 320 (3.6%) died during hospitalization, while 2050 (23.3%) developed a severe complication, and 2175 (24.6%) experienced an extended length of stay. After multivariable analysis adjusting for age, illness severity, trauma burden, and other baseline covariates, frailty (by mFI-11) was independently associated with lower likelihood of routine discharge [adjusted odds ratio (aOR) 0.82, 95% CI 0.77-0.87; P < .001] and development of a severe complication (aOR 1.17, 95% CI 1.12-1.23; P < .001), but not with in-hospital mortality or extended length of stay. Subgroup analysis by age demonstrated robust associations of frailty with routine discharge in advanced age groups (aOR 0.71 in patients 60-80 years and aOR 0.69 in those older than 80 years), which was not present in younger age groups. CONCLUSION: Frailty is an independent predictor of clinical outcomes after tSCI, especially among patients of advanced age. Our large-scale analysis contributes novel insights into limited existing literature on this topic.