Purpose : This study aimed to identify the factors influencing core competencies of disaster nursing among radiation emergency medical response nurses, focusing on nursing professional values, disaster perception, and radiation exposure anxiety. A descriptive cross-sectional design was selected. Methods : The participants were 174 radiation emergency medical response nurses working at radiation emergency medical institutions in South Korea who had completed mandatory education or refresher training and voluntarily agreed to participate. The data were collected using an anonymous online survey conducted from June 4 to June 28, 2024. The survey measured nursing professional values, disaster perception, radiation exposure anxiety, and core competencies of disaster nursing using validated tools. The data were analyzed with descriptive statistics, t-tests, ANOVA, Pearson’s correlations, and multiple regression. Results : The mean scores (out of 5) were 3.55±0.52 for nursing professional values, 3.68±0.40 for disaster perception, 3.73±0.90 for radiation exposure anxiety, and 3.63±0.62 for core competencies of disaster nursing. Core competencies of disaster nursing were positively correlated with nursing professional values (r=.37, p<.001) and disaster perception (r=.37, p<.001). Multiple regression revealed that disaster perception (β=.30, p<.001), participation in radiation emergency exercises (β=.27, p<.001), nursing professional values (β=.24, p=.001), and having a religion (β=.14, p=.034) significantly influenced core competencies of disaster nursing, explaining 27.8% of the variance (adjusted R²=.278, F=14.32, p<.001). Conclusion : The study’s results suggest that beyond simple technical education, enhancing disaster perception, fostering nursing professional values, and systematic participation in exercises can better and effectively improve radiation emergency medical response nurses’ core competencies of disaster nursing.