Aims and objectives The study investigated clinical nurses' critical thinking levels in public hospitals and related factors. Background Since health care environments have become more complex, the critical thinking skills of clinical nurses are more important in daily problem-solving and decision-making processes. However, little research was conducted on this topic among clinical nurses. Methods It was a cross-sectional study at five public hospitals between December 2018 and January 2019. The study followed the STROBE guideline. Data were collected from 559 nurses by a survey consisted of a data form and the Turkish version of the Nursing Critical Thinking in Clinical Practice Questionnaire. Results Nurses' mean critical thinking scores were moderate level. Total critical thinking scores of the clinical nurses significantly differed according to education, hospital type, shift work, professional category and role. There was a significant effect on the total critical thinking scores of the clinical nurses according to variables. Conclusion This study found that critical thinking levels of nurses' working in clinical settings in public hospitals were moderate level. Hospital type, shift work, professional and educational level and role were significantly associated with clinical nurses' critical thinking levels. Relevance to clinical practice This study provides evidence related to the levels of critical thinking of clinical nurses working in public hospitals. Since the critical thinking scores of the manager nurses, daytime working nurses' and nurses with bachelor's and master's degree education are higher, hospital managers may benefit from the study to implement effective strategies to improve the competence of critical thinking levels of nurses.