Background: Emergency and intensive care unit nurses are the main workforce fighting against COVID-19. Their professional identity may affect whether they can actively participate and be competent in care tasks during the pandemic., Objective: To examine the level of and changes in professional identity of Chinese emergency and intensive care unit nurses as the COVID-19 pandemic builds., Methods: A cross-sectional survey composed of the Professional Identity Scale for Nurses plus 2 open-ended questions was administered to Chinese emergency and intensive care unit nurses through an online questionnaire., Results: Emergency and intensive care unit nurses had a medium level of professional identity. Participants' total and item mean scores in 5 professional identity dimensions were higher than the professional identity norm established by Liu (P < .001). The greatest mean item score difference was in the dimension of professional identity evaluation (3.57 vs 2.88, P < .001). When asked about their feelings witnessing the COVID-19 situation and their feelings about participating in frontline work, 68.9% and 83.9%, respectively, reported positive changes in their professional identity., Conclusions: The professional identity of emergency and intensive care unit nurses greatly improved during the early stages of the COVID-19 pandemic. This finding may be attributed to more public attention and recognition of nurses' value, nurses' professional fulfillment, and nurses' feelings of being supported, motivated, respected, and valued., (© 2021 American Association of Critical-Care Nurses.)