There is a dearth of research into the experience of adult diagnosis of autism spectrum disorder, and targeted research is needed to understand the needs of these adults. The aim of this coproduced review was to assess existing qualitative data on the lived experience of receiving an autism spectrum disorder diagnosis, identify recurring themes, and synthesize them into a visual model representing the journey through diagnosis. Using thematic analysis, we analyzed qualitative data from 24 studies of adult experiences of autism spectrum disorder diagnosis from PsycINFO, Embase, MEDLINE, and CINAHL. Thirty-two "descriptive" themes and three superordinate themes were identified. These themes represented how factors relating to identity and relationships are impacted by the diagnosis of autism spectrum disorder and the role of adaptation and assimilation. While the diagnostic process was confusing and disappointing for many, it often led to a sense of relief and clarity regarding past experiences. It created opportunities to connect with other autistic individuals and to access services, though appropriate supports were widely lacking. Recommendations are made that the diagnosis process explicitly considers needs in relation to: the impact of the diagnosis on identity, interactions with other people, choices regarding disclosure, and whether and how to make informed adaptations.