BACKGROUND: Social prescribing involving primary care-based 'link workers' is a key UK health policy that aims to reduce health inequalities. However, the process of implementation of the link worker approach has received little attention despite this being central to the desired impact and outcomes. AIM: To explore the implementation process of such an approach in practice. DESIGN AND SETTING: Qualitative process evaluation of the 'Deep End' Links Worker Programme (LWP) over a 2-year period, in seven general practices in deprived areas of Glasgow. METHOD: The study used thematic analysis to identify the extent of LWP integration in each practice and the key factors associated with implementation. Analysis was informed by normalisation process theory (NPT). RESULTS: Only three of the seven practices fully integrated the LWP into routine practice within 2 years, based on the NPT constructs of coherence, cognitive participation, and collective action. Compared with 'partially integrated practices', 'fully integrated practices' had better shared understanding of the programme among staff, higher staff engagement with the LWP, and were implementing all aspects of the LWP at patient, practice, and community levels of intervention. Successful implementation was associated with GP buy-in, collaborative leadership, good team dynamics, link worker support, and the absence of competing innovations. CONCLUSION: Even in a well-resourced government-funded programme, the majority of practices involved had not fully integrated the LWP within the first 2 years. Implementing social prescribing and link workers within primary care at scale is unlikely to be a 'quick fix' for mitigating health inequalities in deprived areas.