Individuals on the autism spectrum experience high rates of mental health issues. Meta-analyses indicate promising effects of psychological therapies, but challenges remain in ensuring and supporting access. This systematic review identified 12 studies that report on the barriers and facilitators to accessing psychological treatments for mental health or emotional/behavioural challenges for individuals on the autism spectrum. The most commonly reported barrier was a lack of therapist knowledge or expertise in autism or an inability or unwillingness on the part of the therapist to tailor approaches to support the needs of those on the autism spectrum. Fewer studies identified facilitators to accessing services. The findings highlight avenues for improving access to mental health services for individuals on the autism spectrum.