Objective and accurate cognitive assessment scales are essential for guiding cognitive rehabilitation following traumatic brain injury (TBI). The aim of this study was to evaluate the reliability and validity of the Rowland Universal Dementia Assessment Scale (RUDAS) for TBI and to verify the clinical application value. Fifty patients with TBI and 32 matched controls were assessed using the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), and a newly developed Chinese version of RUDAS. These scales were then compared for internal consistency, inter-rater reliability, test‒retest reliability, content validity, construct validity, and diagnostic efficacy. Among the TBI group, the RUDAS demonstrated acceptable internal consistency (Cronbach’s  = 0.733), high inter-rater reliability (intraclass correlation coefficients [ICCs] of 0.910‒0.999), and high test‒retest reliability (total score ICC = 0.938). The correlation coefficients between RUDAS total score and individual subscores were all > 0.5 except for body orientation ( = 0.363), indicating generally good content validity. Total RUDAS scores were moderately correlated with both MMSE total scores ( = 0.701,  < 0.001) and MoCA total scores ( = 0.778,   0.05). A RUDAS score cutoff of 23.5 distinguished TBI patients from controls with 60% sensitivity and 100% specificity. Therefore, the RUDAS demonstrates both good reliability and validity for evaluating cognitive impairments in TBI patients.