Aim To explore experiences of frontline nurse managers during COVID-19. Background The COVID-19 pandemic has complicated care provision and healthcare management around the world. Nurse managers have had to face the challenge of managing a crisis with precarious resources. Little research has been published about the experiences of nurse managers during the COVID-19 pandemic. Methods A qualitative descriptive study of 10 frontline nurse managers at a highly specialized university hospital in Spain was carried out. Semi-structured interviews were conducted between June and September 2020. The Consolidated Criteria for Reporting Qualitative Research checklist was used for reporting. Results Six themes emerged: constant adaptation to change, participation in decision-making, management of uncertainty, prioritization of the biopsychosocial well-being of the staff, preservation of humanized care and 'one for all'. Conclusions This study provides evidence for the experiences of nurse managers during the COVID-19 pandemic. In addition, analysing these experiences has helped identify some of the key competencies that these nurses must have to respond to a crisis and in their dual role as patient and nurse mediators. Implications for Nursing Management Knowing about the experiences of frontline nurse managers during the pandemic can facilitate planning and preparing nurse managers for future health disasters, including subsequent waves of COVID-19.