To determine the effects of non-pharmacological randomised controlled trials in adults with autism, a systematic review was conducted across five electronic databases. A total of 3865 abstracts were retrieved, of which 41 articles met all inclusion criteria: randomised controlled trial; non-pharmacological intervention; adults with autism; and English publication. Twenty included studies had strong methodological quality ratings. No meta-analysis could be performed due to heterogeneity between studies. Articles reported on interventions for (1) social functioning and language skills, (2) vocational rehabilitation outcomes, (3) cognitive skills training, and (4) independent living skills. Social functioning was the most studied intervention. "PEERS for young adults" and "Project SEARCH plus ASD support" interventions had the strongest evidence. Emerging evidence suggests non-pharmacological interventions could be effective.