This paper presents findings of a study exploring professionals’ understanding of the County Lines phenomenon. Employed across two voluntary sector young peoples’ supported accommodation projects a purposeful sample of fifteen (n = 15) practitioners were recruited as study participants. The study purpose was to explore professional perceptions of criminal exploitation in the context of County Lines and identify how practitioners recognised and responded to children and young people at risk. Questions guiding the study included: (1) What are practitioners’ perceptions of criminal exploitation and County Lines? (2) How do practitioners recognise and respond to children and young people at risk? With a review of literature, data collection methods comprised a: (1) case study vignette and (2) self-reporting questionnaire. Utilising aspects of content analysis combining highest frequencies of most common terms and references presented in data, comparable participant responses were coded into four (n = 4) key categories. Categories included: (1) Knowledge of criminal exploitation and County Lines (2) Recognising risk and vulnerability factors (3) Understanding methods of exploitation and responding to risk and (4) Practitioner attitudes, bias and stereotypes. Findings highlight disparities in professionals’ understanding in relation to: (1) what County Lines is (2) how and why some children and young people are criminally exploited in the context of County Lines and (3) how practitioners identify and respond to children and young people at risk. Need for development of enhanced knowledge-depth for safeguarding practice is identified as required around practitioners’ understanding of: (1) risk, vulnerability factors and the signs of criminal exploitation through County Lines (2) importance of ensuring multi-agency statutory safeguarding referrals and responses are undertaken (3) how legal frameworks including the National Referral Mechanism and Modern Slavery Act (2015) can offer victims protection and (4) importance of theoretically informed relationship-based practice with children and young people guided by trauma-informed principles.