The aim of this study was to clarify how nurses who cared of severe COVID-19 patients were affected by Certified Nurse Specialist (CNS) who were responsible for the patient’s family care through their collaboration. Qualitative content analysis method was used in this study. Seven nurses who worked with CNSs between November 2021 to September 2022 were included. The results of this study revealed that the CNSs experienced nursing practice for severely ill COVID-19 patients and their families, and that while the nurses’ internal changes regarding COVID-19 nursing were observed, they also experienced difficulties in working with the CNSs in unusual situations. The results suggest that the CNS’s practice itself may influence the nurses’ practice and have a positive impact on the nurses themselves.