This systematic review (Prospero Registration Number: CRD42019142910) aimed to narratively synthesise technology-aided assessments and treatments of anxiety in individuals with autism spectrum disorder (ASD) for the first time. Sixteen studies were identified: 5 assessment studies and 11 treatment studies. Assessment studies targeted state anxiety using ecological momentary assessment, wearables, or computerised tasks. Treatment studies targeted specific fears/phobias using electronic screen media or transdiagnostic anxiety using telemedicine. Broadly, results indicated technology-aided assessments and treatments may be feasible and effective at targeting anxiety in ASD, except treatments involving social scripts or peer modelling. Assessment results further indicated that state anxiety in ASD has a distinct psychophysiological signature and is evoked by idiosyncratic triggers. However, larger scale studies with representative samples are needed.