This study investigated the dietary behavior of experienced shiftwork nurses and aimed to identify factors related to dietary behavior. This study was a secondary analysis based on the Shift Work Nurses' Health and Turnover study (2018-2021) among Korean nurses. In total, 247 experienced (>12 months) shiftwork nurses were included in this study. The participants' dietary behavior, depression, level of occupational stress, fatigue, physical activity, and general characteristics were measured. Descriptive statistics, Pearson correlation coefficients, independent t-test, one-way analysis of variance, the Kruskal-Wallis test, and multiple regression analysis were conducted. The dietary behavior score of the participants using the Mini-Dietary Assessment Index was 29.35±5.67. Thirty percent of the participants were depressed, the participants experienced moderate occupational stress, and 74.1% of the participants engaged in an inadequate amount of physical activity. The factors influencing shiftwork nurses' dietary behavior were having child(ren) (β=.16, p=.027), depression (β=-.13, p=.032), level of occupational stress related to occupational climate (β=-.13, p=.035), and an inadequate amount of physical activity (β=-.17, p=.006). These factors explained 10.4% of the variance in experienced shiftwork nurses' dietary behavior scores. Experienced nurses with child(ren) tended to have healthier diets. However, a higher level of occupational stress related to occupational climate, depression, and engaging in an inadequate amount of physical activity were associated with a higher risk of having an unhealthy diet. Therefore, strategies are needed to encourage physical activity and alleviate adverse occupational climate and depression among experienced nurses.