Background Under the COVID-19 pandemic, nurses are the mainstay in the fight against the pandemic. Purpose To evaluate potential impact of the pandemic on nurses’ professional identity. Method Self-report questionnaires were distributed online. Data collected were compared with available norms. Multivariate logistic regression analyses were employed to calculate the OR of frontline vs. nonfrontline nurses. Findings The mean of the total score of the scale was 121.12 out of 150. Both the total score and scores on the five dimensions were significantly higher than norms. Frontline nurses had a significantly higher professional identity than non-frontline nurses (total score: odds ratio [OR], 1.19; professional identity evaluation: OR, 1.27; professional social support: OR, 1.18; professional social proficiency: OR, 1.33; and dealing with professional frustration: OR, 1.19). The most frequently mentioned tags were Hope, Frontline, Protection, Outbreak, Work, Situation. Discussion COVID-19 outbreak was associated with an enhancement in the professional identity of nurses., Highlights • This study established that nurses experienced a high level of professional identity during the outbreak of COVID-19. • This study found that working on the frontline could be an important factor related to a high level of professional identity. • This study found that in facing the COVID-19 outbreak, nurses experienced an ever-increased professional and social responsibility, and recognized the value of nursing. • The main findings indicate the potential for enhancement of professional identity during times of extreme stress in the health care system, which provides opportunities for future research and practice.