Young people moving from child and adolescent secure hospitals present with complex needs and vulnerabilities and are more likely to experience poor transition outcomes. Previous research has indicated the presence of several risk factors in periods of transition, such as poor liaison among services, lack of proper planning, shortage of beds in adult services, multiple transitions and lack of emotional readiness. However, little evidence exists about the processes and outcomes of transitions from adolescent secure services to adult settings. This study aims to bridge the gap in the existing literature by exploring the views and experiences of key professionals involved in the transition process from six adolescent medium secure units to nine adult secure and community services in England. Thirty-four key workers from 15 child and adolescent (N = 21) and adult (N = 13) forensic hospitals were interviewed to provide information about potential barriers and facilitators to transitions. Face-to-face semi-structured interviews were conducted between January 2016 and December 2017. Thematic analysis was used to identify challenges and facilitators to transitions. Three primary themes were identified: (1) transition processes and preparation; (2) transition barriers and challenges; (3) success factors to transition. Key differences in adult and adolescent service care-models and lack of emotional and developmental readiness to moving onto adult-oriented settings constitute major barriers to positive transition outcomes. Practice and policy implications are considered to address the need for service transformations.