For a social prescribing intervention to achieve its aims, clients must first be effectively engaged. A ‘link worker’ facilitating linkage between clients and community resources has been identified as a vital component of social prescribing. However, the mechanisms underpinning successful linkage remain underspecified. This qualitative study is the first to explore link workers’ own definitions of their role in social prescribing and the skills and qualities identified by link workers themselves as necessary for effective client linkage. This study also explores ‘threats’ to successful linked social prescribing and the challenges link workers face in carrying out their work. Link workers in a social prescribing scheme in a socioeconomically deprived area of North East England were interviewed in two phases between June 2015 and August 2016. The first phase comprised five focus groups (n = 15) and individual semi-structured interviews (n = 15) conducted with each focus group participant. The follow-up phase comprised four focus groups (n = 15). Thematic data analysis highlighted the importance of providing a holistic service focusing on the wider social determinants of health. Enabling client engagement required ‘well-networked’ link workers with the time and the personal skills required to develop a trusting relationship with clients while maintaining professional boundaries by fostering empowerment rather than dependency. Challenges to client engagement included: variation in the volume and suitability of primary-care referrals; difficulties balancing quality of intervention provision and meeting referral targets; and link workers’ training inadequately preparing them for their complex and demanding role. At a broader level, public sector cuts negatively impacted upon link workers’ ability to refer patients into suitable services due to unacceptably long waiting lists or service cutbacks. This study demonstrates that enabling client engagement in social prescribing requires skilled link workers supported by healthcare referrer ‘buy-in’ and with access to training tailored to what is a complex and demanding role.