Phenomenon: Professional identity formation is a key component of health professional education. Changing expectations of healthcare requires more than competencies, but also an ingrained responsibility to patients, with our values and behaviors aligned with community expectations of patient-centered health professionals. Research into professional identity formation has focused on nursing and medical training, and, although allied health professionals make up one third of the workforce, research is uneven across these disciplines. Health professions educators from these under-researched disciplines have less guidance for how to support students’ professional identity, meaning students may graduate with less mature professional identities. This systematic literature review synthesizes the research on professional identity formation across nine similar allied health disciplines. The purpose is to guide health professions educators in the formation of professional identity in allied health students. Approach: We carried out a systematic literature review, registered on Prospero, following the PRIMSA framework, to find, appraise, and synthesize research on professional identity for nine allied health professions. We synthesized extracted data using a narrative synthesis with convergent qualitative meta-integration of qualitative and quantitative data. Results: Our database searches combined with ancestry and forward searching resulted in 70 studies that met inclusion criteria. Studies came from 17 countries, from seven of the included disciplines (art therapy, dietetics, occupational therapy, physiotherapy, podiatry, psychology, and speech pathology) and from undergraduate, postgraduate, and new graduate perspectives. We found professional identity was influenced by the places of learning (curriculum and clinical experiences or placements), interactions with people (relationships with academics, peers, supervisors, patients,and role models), and educational practices engaged (dialogue, reflection, processing challenges), each acting on the individual person (student or new graduate) who also brought unique characteristics and experiences. Insights: This model of influences can inform health professions education to enable students to develop and graduate with a stronger professional identity formation.