The World Health Organization and the International Council of Nurses recognises the importance of nurses' involvement in disaster preparedness and response. The aim of this study was to describe and compare self-reported disaster nursing competence (DNC) among nursing students (NSs) and among registered nurses (RNs) with professional experience. Further to investigate possible associations between self-reported DNC and background factors. A cross-sectional study was conducted of 569 NSs and 227 RNs. All respondents completed the 88-item Nurse Professional Competence Scale, including three items assessing DNC. Significant differences were found among the NSs depending on which University/University College they had attended. RNs reported significantly higher overall DNC and better ability to handle situations involving violence, and to apply principles of disaster medicine during serious events. RNs working in emergency care reported significantly better DNC ability, compared with RNs working in other areas of healthcare. Multiple linear regression analysis showed that working night shift and working in emergency care were positively associated with high self-reported overall DNC. The results indicate that workplace experience of serious events increase the readiness of registered nurses to handle violence, to act in accordance with safety regulations, and to apply principles of disaster medicine during serious events.