Background A nurse's role in caring for the dying is fraught with ethical, professional, and psychosocial challenges that impact how they perceive their roles as professionals. When unsupported, nurses caring for the dying experience burnout, career dissatisfaction and leave the profession. Better understanding of how caring for the dying affects the professional identity formation (PIF) of nurses will guide efforts to better support nurses. Methods Guided by new data on the subject, we adopt the theoretical lens of the Ring Theory of Personhood (RToP) to evaluate how caring for the dying impacts the values, beliefs, principles, professional identities and personhood of nurses. We employ Krishna's Systematic Evidence-Based Approach (SEBA) to guide the design and piloting of the semi-structured interview tool. Results Analysis of interviews with eight senior nurses in Supportive, Palliative and Oncology care revealed three domains: Identity 1) Formation; 2) Conflict and 3) Refinement. Identity Formation occurs early in a nurse's career, upon entering a new specialist field, and at the start of Supportive, Palliative and Oncology care. Identity Formation reveals significant changes to how self-concepts of professional identities are tied to individual concepts of personhood. Caring for the dying, however, resulted in Conflicts between values, beliefs, and principles within regnant concepts of personhood and their professional duties. These conflicts are captured as conflicts within ('disharmony') and/or between ('dyssynchrony') the rings of the RToP. These conflicts can result in changes to self-concepts of personhood and professional identities. Identity Refinement sees experience and timely support helping nurses attenuate the impact of difficult experiences. This reduces the risk of burnout and mitigates changes to their professional identities. Identity Refinement helps them develop a 'rooted identity' which remains relatively consistent in the face of adversity. Conclusions Ongoing Identity Construction amongst nurses, particularly in caring for the dying, underscore the host organisation's role in ensuring structured, longitudinal, accessible, and personalised assessments and support of nurses, especially when they are prone to dyssynchrony and disharmony whilst caring for the terminally ill. Further study into assessment methods and the role of the environment is critical.