Background Food art therapy (FAT) has multiple modalities in which cognition, emotion, and social changes are stimulated. The purpose of this study was to design a multimodal approach to a food art therapy (MM‐FAT) program and identify its effects on cognitive ability, daily living functioning, depression, self‐esteem, self‐efficacy, self‐expression, and social functioning in individuals with mild cognitive impairment (MCI) and mild dementia by employing a mixed methods research design. Methods The participants included 39 patients from a public dementia care centre in Seoul, Korea. The intervention group, which comprised 20 participants, received 12 MM‐FAT sessions 3 times a week for 4 weeks, and the control group, which included 19 participants, received usual care. The MM‐FAT program was evaluated based on its effectiveness on cognitive, daily living, emotional, and social functioning outcome measures at three time points using repeated measures analysis of variance. Semi‐structured interviews (n = 9) were conducted to evaluate the overall experience of the MM‐FAT program and its outcomes. Results The findings reveal that MM‐FAT has a positive effect on the cognitive, emotional, and social functioning of individuals with MCI and mild dementia. However, there were no enhancements in individuals' daily living functioning, and the lasting effects of the intervention could not be assessed. Cognition and depression increased significantly at the end of the MM‐FAT program. Self‐expression and self‐efficacy were significantly higher in the MM‐FAT group than in the control group. The semi‐structured interviews revealed improvements in participants' behaviour, communication, and interaction. Conclusion This mixed methods study focused on individuals with MCI or mild dementia contributes to an understanding of the effectiveness of a FAT program employing a multimodal approach. Despite the COVID‐19 pandemic, the study was able to enrich the effects of MM‐FAT on cognitive, emotional, and social functioning through qualitative findings.