Background <p>Generative artificial intelligence such as ChatGPT play a key role in enhancing self-directed learning and critical thinking, yet few studies have explored their use among nurses. This study aims to examine the interrelationships among ChatGPT usage, self-directed learning, and critical thinking in Taiwanese school and university nurses.</p> Methods <p>A cross-sectional survey used a nationwide stratified random sample of 600 nurses from 4,304 schools and universities. Instruments included the Critical Thinking Inventory, ChatGPT Adoption, and Self-Directed Learning Scale.</p> Results <p>Among 413 respondents, younger and more educated nurses reported higher ChatGPT usage. self-directed learning, frequent ChatGPT usage, and employment at the junior high school level were significantly associated with higher critical thinking, with self-directed learning showing the strongest association.</p> Conclusions <p>This study of nurses serving schools and higher education institutions reported the associations of ChatGPT usage, with critical thinking and self-directed learning. Given the cross-sectional and self-reported nature of the data, the findings highlight associations that may inform future research on AI integration in education.</p> Implications <p>The findings suggest that promoting self-directed learning and the purposeful use of ChatGPT is significantly related to critical thinking among school nurses. Educational policies and professional development programs should prioritize these strategies, particularly for those in junior high schools or larger student populations, to support informed and autonomous clinical decision-making.</p>