Purpose: This study aimed to develop a program to promote obesity prevention behaviors for pre-schoolers and to confirm the effectiveness of the program in Korea. Methods: The program comprised 8 sessions for 4 weeks including combined classroom lectures and physical activities. A non-equivalent control group pre-post test study design was used, and seventy two children, aged 5 to 6 years (experimental group: 33, control group: 39) and their parents participated in the study. To examine the effectiveness of the program, children’s knowledge, intake of sugar-added beverages and fruits & vegetables, time of outdoor play and screen time, and parental self-efficacy were measured. Data were analyzed with SPSS/WIN ver. 22.0 and R 4.0.2, using descriptive analysis, chi-square test, Fisher’s exact test, the independent t-test, and Analysis of covariance (ANCOVA). Results: The results showed that the experimental group reported significantly increased knowledge (p < .001) and longer time of outdoor play on weekends (p = .033). However, there were no significant differences in the intake of sugar-added beverages and fruits & vegetables, screen time, and parental self-efficacy in the two groups. Conclusion: This study confirms the applicability of an obesity prevention intervention at kindergartens in Korea. The results can be used as basic data for the study of childhood obesity prevention in Korea.