Background The support needs of people with neurodevelopmental disorders are not sufficiently met during the initial years of adulthood. Aim To evaluate feasibility and preliminary effects of a novel programme designed to empower young adults with autism spectrum disorder (ASD) and/or attention deficit hyperactivity disorder (ADHD) to make progress within significant life domains (i.e. work, education, finance, housing/household management, health, leisure/participation in society, and relationships/social network). Material and Method TRANSITION is a 24-week programme that combines group-based workshops with personalised support based on goal attainment scaling. The study enrolled 26 young adults (50% females; age 17–24 years) in the normative intellectual range, diagnosed with ASD (n = 8), ADHD (n = 4), or both (n = 14). The intervention was delivered by the regular staff of publicly funded psychiatric services in Stockholm, Sweden. Results The programme was possible to implement with minor deviations from the manual. Participants and staff generally viewed the intervention positively, but also provided feedback to guide further improvement. There was a high degree of attendance throughout, with 21 participants (81%) completing the programme. All completers exceeded their predefined goal expectations within at least one domain. Conclusions The TRANSITION-programme is a promising concept that deserves further evaluation.