Background: Social media has become an integrated part of nursing profession, requiring nursing students to develop confidentiality and professional fitness to practice. The aim of this study was to investigate nursing students’ usage, professionalism and attitudes toward social media. Methods: A cross-section study was conducted online among undergraduate nursing students (n = 654). Questionnaires of self-directed learning, self-efficacy and usage and views toward social media were administered. Ethical considerations: Ethical approval was obtained from the Hubei University of Chinese Medicine. Results: All participants were social media users. QQ (93.2%) was the most frequently used. 74.5% respondents spent 2–6 h on social media daily. The majority held positive attitudes toward social media. Year group and gender had influence on perceptions and attitudes toward social media. Furthermore, 81.5% students believed that social media positively influenced self-directed learning. Self-directed learning and learning motivation acted as predictors of the attitudes toward social media. Meanwhile, 67.3% students had posted personal photos and videos online, and 82.4% of them did not have privacy setting on social media. In addition,13.8% students attacked others or posted improper photos online. 22.9% participants witnessed improper posts from schoolmates or teachers, such as complaints about schoolmates or teachers (22.2%), foul language (11.1%), violence (3.9%), sexually suggestive photos (2.6%) and patient confidentiality (0.7%). In all, 15.0% respondents accepted “friend request” from patients. A total of 58.2% students were not aware of professional standards of behavior online for health care providers. In addition, 52.3% participants insisted that it is essential to develop social media and professionalism course for nursing students. Conclusion: Nursing students use social media extensively. Some students are at risk of carrying out unprofessional behavior which have detrimental effects on students’ future opportunities. This suggests that best practices and training in nurse education should be implemented to help students to be informed of professionalism.