To explore the experiences of musculoskeletal (MSk) physiotherapy independent prescribing in primary care from the perspectives of physiotherapists and General Practitioners (GPs) and identify the implications these have for contemporary physiotherapy practice in primary care. Legislative change in the United Kingdom (UK) in 2013 enabled physiotherapists holding a postgraduate non-medicalprescribing qualification to independently prescribe certain drugs that assist in patient management. Independent prescribing by physiotherapists is a relatively contemporary development in role change and purpose, occurring alongside the development of physiotherapy first contact practitioner (FCP) roles in primary care. A critical realist approach was used, with qualitative data collected via 15 semi-structured interviews with physiotherapists and GPs in primary care. Thematic analysis was applied. Fifteen participants were interviewed (13 physiotherapists, 2 GPs). Of the 13 physiotherapists, 8 were physiotherapy independent prescribers, 3 were MSk service leads, and 3 were physiotherapy consultants. Participants worked across 15 sites and 12 organisations. Whilst physiotherapists were empowered by their independent prescribing qualification, they were frustrated by current UK Controlled Drugs legislation. Physiotherapists reported vulnerability, isolation, and risk as potential challenges to independent prescribing, but noted clinical experience and 'patient mileage' as vital to mitigate these. Participants identified the need to establish prescribing impact, particularly around difficult to measure aspects such as more holistic conversations and enhanced practice directly attributed to prescribing knowledge. GPs were supportive of physiotherapists prescribing. Establishment of physiotherapy independent prescribing value and impact is required to evaluate the role of, and requirement for, physiotherapy independent prescribers within primary care physiotherapy FCP roles. Additionally, there is a need for a review of physiotherapy prescribing permitted formulary, and development of support mechanisms for physiotherapists at individual and system levels to build prescribing self-efficacy and autonomy, and to advance and sustain physiotherapy independent prescribing in primary care.