PURPOSE: The purpose of this study was to investigate the effect of multimodal intervention through VR (virtual reality)-based immersion program on the cognitive function and brain activity of patients with mild cognitive impairment. METHODS: The subjects of the study were 10 people in the experimental group who applied a complex intervention that performed cognitive tasks using the movement of the upper extremities through the VR program, and 10 people in the control group who received traditional occupational therapy. After the study intervention was applied 5 times a week, 30 minutes a day for a total of 8 weeks, LOTCA-G(Lowenstein Occupational Therapy Cognitive Assessment for Geriatric Population) and NIRSIT LITE were used to compare. RESULTS: Significant differences in cognitive function and brain activity were noted between the pre- test and post-test in the experimental group. Brain activity showed statistically significant differences in four channels of the working memory domain and one channel of the metacognitive domain (p < . 05). Comparative analysis of the difference between the two groups revealed statistically significant differences in cognitive function and brain activity. The brain activity showed statistically significant differences in three channels of the working memory domain and one channel of the metacognitive domain (p < .05). CONCLUSION: Through the results of this study, it was found that the complex intervention of performing cognitive tasks using upper extremity movements through the VR program had a positive effect on the cognitive function of patients with mild cognitive.