To be more successful in preventing malnutrition for older adults living at home, there is a need for better methods to characterize their food behavior, as well as there is a need for health-supporting technologies focusing more on individualized contextual preferences. This study reveals how photos can be used to characterize older adults’ food-related behavior and preferences, and how photo elicitation can be used to design an eating environment in mixed reality for older solitary adults. This study is based on a sample of 22 older adults, who took in total 153 pictures of their meals, and a workshop using photo elicitation with 16 older adults in a community center. The findings revealed how photos can be used as a self-monitoring process to create meaningful and rich in-depth information on food-related behavior of older adults living at home. Photo elicitation can be used as a supplement to characterize older adults’ food-related behavior and preferences in a mixed reality environment. Further, we outline both advantages and limitations of using photo elicitation in a context of human-computer interaction.