This study aimed to develop the Korean Health Behavior for Dementia Prevention Scale (K-HBDP) and test its validity and reliability. Methods: In this methodological study, the K-HBDP scale was administered to 216 community-dwelling older adults (aged 65 or older) in 2020 in seven cities of western Korea using convenience sampling. Item analysis, construct validity, item convergent and discriminant validity, criterion validity, and internal consistency reliability were evaluated using SPSS for Windows 27.0. Results: The scale includes 23 items and five subscales: cognitive social activities, healthcare management, lifestyle, smoking and drinking, and eating habits, and the cumulative variance explained by the factors was 66.8%. Cronbach’s ⍺ for internal consistency of the total scale was .90 and ranged from .65 to .89 for all subscales. Item convergent and discriminant validity of the K-HBDP were confirmed. Criterion validity was demonstrated with the Health Promoting Lifestyle Profile-II. Conclusion: The findings suggest that K-HBDP scale can be used to measure healthy activities to prevent dementia in older adults. The use of this tool is expected to help develop interventions, educational materials, and training programs to improve nursing practice.