The COVID-19 has caused high morbidity and mortality in vulnerable people, such as those affected by chronic diseases, and case-management nurses (CMNs) are reference professionals for their health care and management. The objective of this study is to better understand the discourse, experiences, and feelings about the professional performance of CMNs during the pandemic. A qualitative study was conducted by conducting semi-structured interviews with CMNs (n = 31) from the province of Seville (Spain) and performing a narrative discourse analysis. The Atlas Ti 6.2 software program was used. Two categories were defined: 1. CMNs' competencies (76 verbatim testimonies); and 2. Consequences of the COVID-19 pandemic (61 verbatim testimonies). This study was granted due permission by the Research Ethics Committee belonging to the University of Seville, under protocol code: 1139-N-22. The pandemic caused an increase in CMNs' workload, and they had to assume their usual care tasks for vulnerable populations in addition to simultaneously prioritizing assistance in nursing homes. We can highlight CMNs' adaptation to the pandemic situation and to these new requirements in the context of their significant social commitment to the advanced practice of the profession, a commitment that is closely related to leadership. We should also indicate that interpersonal relationships were improved, and that there was technological progress. Some CMNs mentioned an increase in their workload and reported experiencing burnout syndrome. We conclude that CMNs' management of health care during the pandemic has been extraordinary, especially in regard to the most vulnerable populations of patients, including individuals with chronic diseases and institutionalized older adults, a fact that has been valued by the institutions and by society in general.