“Ugly food” refers to agricultural products that are discarded because their appearance is not attractive, even though their nutritional content is unaffected. In this study, protection motivation theory (PMT) was applied to analyze whether an individual’s awareness of food waste problems affects their “ugly food” purchase intention. Hence, the relationships between awareness of food waste problems, threat appraisal (severity and vulnerability), coping appraisal (response efficacy and self-efficacy), and ugly food purchase intention were analyzed. Additionally, a moderating effect analysis was conducted per consumer age. Descriptive statistical analysis, frequency, and SPSS reliability analysis were used, including confirmatory factor analysis, structural equation modeling, and multi-group analysis of the Amos program. For the final analysis, 361 samples were used. Results showed that awareness of food waste problems positively affected severity and vulnerability, response efficacy, and self-efficacy. Moreover, severity positively affected ugly food purchase intention and vulnerability did not. Response and self-efficacy positively affected ugly food purchase intention. In the moderating effect analysis per consumer age, the difference between severity and ugly food purchase intention and vulnerability and ugly food purchase intention was significant. This study has various academic and practical implications, and presents several strategies to reduce food waste to contribute to a sustainable future environment. It is also the first study linking the food waste problem, PMT, and ugly food purchase behavior.