Purpose <p>Anxiety prevalence is higher for autistic adults than the general population, yet there is no consensus on whether self-report questionnaires provide internally consistent measurements. This review aimed to identify and narratively compare the internal consistency of all available self-report anxiety measures for autistic adults, and meta-analyse the measures with enough studies.</p> Methods <p>Six databases were searched to identify relevant literature. After eligibility criteria were applied, 27 articles were retained. Included papers were evaluated for risk of bias using bespoke criteria.</p> Results <p>The Generalised Anxiety Disorder seven-item questionnaire, Liebowitz Social Anxiety Scale, and Depression Anxiety Stress Scale (21-item – anxiety subscale [DASS-21]) were meta-analysed as they were examined in sufficient numbers of studies. Pooled Cronbach’s of 0.91 (CI 0.91–0.92), 0.97 (0.96–0.97), and 0.87 (0.83–0.92), respectively, were identified. Acceptable heterogeneity was found for all measures except the DASS-21 (I² = 95.4%). Pooled internal consistency was comparable to equivalent measures used with general population samples. A complementary narrative review revealed that internal consistency across all 27 studies ranged from good to excellent.</p> Conclusion <p>Published data suggest self-report anxiety measures have excellent internal consistency when completed by autistic adults. Future studies should explore complementary psychometric properties and include autistic samples with intellectual disabilities to replicate the findings.</p>