Social prescribing is an increasingly popular approach to promoting health and well-being, by addressing the wider determinants of health such as physical inactivity, social isolation and financial insecurity. Social prescribing link workers (SPs) connect people to local, non-clinical services. As part of the NHS Long Term Plan, NHS England aims to recruit 1,000 SPs across England by 2021. Understanding the role of SPs, including challenging aspects of the role and the types of training and support needed by SPs is crucial to optimising the effectiveness of social prescribing. Semi-structured qualitative interviews were conducted with nine SPs from five NHS and voluntary sector organisations in London to explore the role of SPs and identify SP training and support needs. Interviews were analysed thematically and three key themes emerged for which SPs needed particular support: defining and promoting their role; supporting clients with complex needs and coping with the emotional demands of their role. SP perceptions of training and future training needs is presented as a fourth theme. Most SPs felt that the initial training received for their role did not prepare them for the most demanding aspects of their roles. The findings of this study support the assertion that the social prescribing link worker role is complex and challenging. SPs are required to have in-depth knowledge of local services, which is built over time and makes retention in the role of high importance. Steps have been taken to develop online resources to support SPs, however, there may be a need for more comprehensive training, especially in mental health. SPs benefit from access to peer or one-to-one support to help them manage the emotional demands of the role and could benefit from the formation of local networks, especially for SPs working in isolation.