The effect of ever-increasing life expectancy on global demographics has had a significant impact on many professional landscapes, not only in social services and healthcare but more broadly. This instrumental case study explores professional healthcare musicians' work through their collaborative, socially engaged music-making practice in eldercare hospital wards. Two healthcare musicians were interviewed, and their work and professional practices were observed in the infection and orthopedic wards of an arts-promoting eldercare hospital. The empirical material was analyzed using thematic analysis, and finalized by instrumentalizing the case through the theoretical lens of gerotranscendence and music professionalism. The findings of the study open up a diversified understanding of aging as a transformative process of change and development, and reveal how professional music practices can support a holistic care and healthcare approach. Furthermore, it is discovered that healthcare musicians' work as a socially engaged approach to professionalism reframes musicianship as part of an expanding professionalism, and calls for further development of higher music education as well as in-service training in the field of music.