This study aimed to develop, and evaluate the effectiveness of, a home economics dietary education program that could be used to improve high school students’ sustainable dietary competencies. To achieve this goal, learning objectives and elements were selected for the education program to improve the students’ sustainable dietary competency. The content validity of this program was verified with numerous experts. After implementing the new educational program, its effect on high school students' sustainable dietary competencies was assessed through pre- and post-tests. The results of this study are summarized as follows. First, through the textbook analysis, the necessity of developing an educational program that can cultivate the three areas that constitute a sustainable diet (environment, health, and consideration) was confirmed. Second, a total of nine teaching and learning plans for sustainable dietary education programs were developed. From there, content validity verification was conducted by experts, indicating that the developed educational program was highly applicable in the field. Third, after the implementation, a survey was conducted based on a questionnaire consisting of 20 items related to three areas of sustainable diet, while the pre- and post-test assessment indicated statistically significant differences in all three areas: environment (pre: 3.40, post: 4.46, p<.001), health (pre: 3.15, post: 4.32, p<.001), and consideration (pre: 3.46, post: 4.48, p<.001). It is expected that the educational program developed in this study will be used as a basis for dietary education that fosters food citizenship in high school home economics courses.