Background: Despite evidence to support the effectiveness of psychoeducation for people experiencing mental health difficulties and their families, understanding issues around the implementation of such programmes is limited. Aim: The aim of this scoping review was to synthesise the peer-reviewed literature on barriers and enablers influencing the implementation of group psychoeducation in adult mental health services. Methods: Using a pre-defined search strategy and PRISMA guidelines, four databases were systematically searched. Two reviewers independently screened and applied exclusion/inclusion criteria. Qualitative, quantitative, and mixed-methods studies were included if they provided empirical evidence on the barriers and enablers. Three reviewers independently extracted data. Following this, data were analysed using a five-level implementation framework. Results: Eight articles met the inclusion criteria. Barriers to implementation were identified at all five levels of the framework: participant; practitioner; intervention; organisational; and structural level. Enablers to implementation were evident at four levels: participant; provider; intervention; and organisational level. Conclusions: The findings of the review provide preliminary information on factors that impact implementation. However, large-scale studies informed by implementation theories are required. In addition, other studies are needed to address the potential impact of different models of intervention and explore strategies to minimize obstacles and support sustainability.