Objective: The study’s aim was to evaluate the validity of the Korean version of the University of California San Diego Performance-based Skills Assessment, Validation of Intermediate Measures (K-UPSA-2-VIM) in patients with dementia (D), mild cognitive impairment (MCI), and cognitive normal control group (CN). Methods: Study participants were 25 patients with D, 43 patients with MCI, and 111 controls with CN group, respectively. For cognitive assessment, Mini Mental State Examination, Consortium to Establish a Registry for Alzheimer’s Disease neuropsychological battery, and Clinical Dementia Rating were used. For functional assessment, Barthel-Activities of Daily Living, Instrumental Activities of Daily Living, Dementia Screening questionnaire, and K-UPSA-2-VIM were used. Results: Statistically significant differences were observed in all subdomains and total score of the K-UPSA-2-VIM among three cognitive groups. K-UPSA-2-VIM demonstrated 75.7% of sensitivity and 65.1% of specificity, with an area under the curve (AUC) of 0.731 (95% confidence interval [CI]: 0.641-0.821, p<0.001) in discriminating between CN and MCI groups. In discriminating between MCI and D groups, 76.7% of sensitivity and 64.0% of specificity, with an AUC of 0.706 (95% CI: 0.580-0.833, p=0.005) were demonstrated. Conclusion The K-UPSA-2-VIM is useful to evaluate activities of daily living function in Korean patients with D and MCI.