The present review evaluated studies which effectively employed cognitive behavioural therapy (CBT) to alleviate symptoms of common mental health problems in young people with autism spectrum disorder (ASD). It assessed the modifications applied to CBT and compliance with recent guidelines from the National Institute of Health Care Excellence (NICE). Systematic searches of electronic databases, reference lists, and journals identified 12 studies meeting predetermined inclusion criteria. Results indicated that modified CBT yielded reductions in anxiety, obsessive-compulsive disorder (OCD), and depression. There was a lack of gold standard research into the effects of CBT for disorders other than anxiety. A greater number of modifications than recommended by NICE were consistently employed, including disorder-specific modifications. Implications for clinical intervention and future research are discussed.