Purpose: Neonatal nurses are expected to have clinical competency to provide qualified and safe care for high-risk infants. An educational intervention to enhance nurses’ clinical competence is often a priority in the nursing field. This study was conducted to explore nurses’ perceived importance and performance confidence of nursing care activities in neonatal intensive care units. Methods: One hundred forty-one neonatal nurses from seven hospitals across South Korea participated in the online survey study. The scale of neonatal nursing care activity consisted of 8 subdomains including professional practice (assessment, diagnosis, planning, intervention, evaluation, education, research, and leadership). The Importance-Performance Matrix was used to analyze the importance of and confident performance in each of the nursing subdomains. Results: Both importance and performance confidence increased as nurses’ age (p=.042 and p<.001) and clinical experience (p=.004 and p<.001). Participants scored relatively higher in importance and performance confidence in the professional practice subdomains (assessment, intervention, evaluation), but scored lower in the education and research subdomains. Conclusion To provide evidence-based nursing care for high-risk infants in neonatal intensive care units, educational interventions should be developed to support nurses based on the findings of the research.