The diagnostic prevalence of autism is growing with a considerable increase shown globally (Maenner et al., 2023; Zeiden et al., 2022) over previous decades (Russell et al., 2022). Moreover, the rates in which anxiety co-occurs with autism is high, with estimates thought to range between 40% to 50%. Anxiety is seen to exacerbate core autism features and impact social and emotional adaptation, relationships, educational performance (Fujii et al. 2012; Reaven et al. 2011; Wood et al. 2015), and the individual’s quality of life (van Steensel et al., 2012). Parental involvement is argued to have significance clinically when treating autistic youth, with research arguing that including parents has the potential to enhance interventional outcomes. The current review aims to evaluate the effectiveness of cognitive and behavioural interventions including parental involvement for anxiety in autistic youth. This was achieved by evaluating the two primary research questions. This review seeks to investigate the effectiveness of parental involvement within cognitive and behavioural interventions targeting anxiety in autistic youth, evaluating outcomes across all measures, not only anxiety. A secondary aim for this review was to investigate whether the degree of parental involvement was impactful upon intervention effects. Studies were included if they: identified anxiety as their primary outcome measure, aimed to reduce or treat anxiety in youth who were school aged (4-18 years) with either a diagnosis of autism and heightened anxiety, included parents, used quantitative research methods, measured at least at pre-intervention and post-intervention. A systematic search of several electronic databases including PsychINFO, PubMed, SCOPUS, embase, and Cochrane Library yielded 3610 citations. Following removal of duplicates, abstract and title screening, full text review, and forward and backward citation searches, 18 studies met eligibility criteria and were included. Of these studies 13 were Randomised Control Trials (RCT) and five were quasi-experimental (QE). Risk of bias was assessed using both the Risk of Bias 2 (RoB2) and the Risk of Bias in Non-randomised Studies of Intervention – version 2 (ROBINS-IV2). The review found marked improvements across all measures of anxiety. The results consistently highlighted reductions in primary anxiety scores, clinical severity of anxiety, and notable improvements in functional measures. Although, some sub-scales demonstrated minimal and insignificant improvement or decline. Moreover, some intervention gains were seen in the broader familial unit. Some limitations were present including broad inclusion criteria, and issues with generalizability. The review included studies that showed a broad range of participant ages, not accounting for developmental differences. Finally, some issues with generalisability may be present as the participants were predominantly male. However, this limitation was to be expected as males are over represented in autism diagnosis.