Women are increasingly being referred to physiotherapy for upper-limb dysfunction (ULD), a commonly reported side-effect of breast cancer treatment. Physiotherapists face many challenges deriving from a lack of research into the management of ULD, its pathophysiology and natural history. Evidence supports the need to gain insight into the experiences of physiotherapists caring for patients with ULD to improve understanding of this area of practice. The aim in this study was to explore physiotherapists’ experiences of managing ULD due to breast cancer treatment based on a qualitative research design, underpinned by a hermeneutic phenomenological approach. Six physiotherapists based in the UK were interviewed face-to-face, using in-depth techniques. The data was analysed using the Interpretative Phenomenological Analysis (IPA) method. Three master themes were identified from the interviews: (1) Dealing with uncertainty of best practice (2) Gaining confidence in practice (3) Being able to make a difference. It was concluded that the participants experienced managing ULD due to breast cancer treatment meaningfully in individually varied ways. All participants acknowledged the significant psychological, social and physical implications of ULD and perceived physiotherapy to be beneficial for people with ULD. They also identified a need for better patient and healthcare professional awareness of ULD and the role of physiotherapy in ULD management.