IntroductionOlder people admitted to hospital are highly susceptible to functional decline and related complications. Care supporting their functioning is complex and requires healthcare professionals working in concert, with nurses playing a central role. Yet, little is known about nurses' perceptions of interprofessional collaboration (IPC) in care supporting functioning in acutely admitted older people. To fill this knowledge gap, we elucidate the perspectives of nurses in Ontario, Canada, on IPC in care supporting older people's functioning during a hospital stay.MethodsWe employed a qualitative methodology in conjunction with a qualitative descriptive design. Thirteen focus groups were held with a purposeful, criterion‐based sample of 57 acute care nurses practising in a range of acute care settings (e.g. Emergency, General Medicine, General Surgery, Intensive Care, Coronary Care). Data were thematically analysed.ResultsWe identified two overarching themes: (1) IPC is improving, but nurses are excluded from decision‐making and (2) nurse advocacy causes friction with other professionals. The first theme captures nurses' perception that IPC in older people's care is improving, but nurses are marginalised in interprofessional decision‐making. As a result, nurses perceive that their knowledge is devalued, and their contributions to care supporting older people's functioning are undermined. The second theme underlines a tension between interprofessional team practices and patient‐ and family‐centred care, while also demonstrating nurses' increasing willingness to act as patient and family advocates.ConclusionsFindings can be used to enhance IPC in care supporting the functioning of acutely hospitalised older people. To improve IPC, clinical and administrative leaders should cultivate more egalitarian team relationships that encourage nurses to contribute to decision‐making and advocate on behalf of older patients and their families.