The objective of this study was to examine the relationship between sensory hypersensitivity and restricted interests and repetitive behaviours associated with autism spectrum disorder and their typically-developing peers. Furthermore, the aims included the examination of the relationship across sensory modalities and various types of restricted interests and repetitive behaviours. Data were collected from the parents of 114 children: 49 of whom were diagnosed with autism spectrum disorder and 65 typically-developing children. Parents completed the Sensory Profile 2 -- Child Version and the Repetitive Behaviours Questionnaire, Second Edition. The results suggested that sensory hypersensitivity is strongly related to the core autism spectrum disorder symptom of repetitive behaviours. This relationship was not specific to autism spectrum disorder; repetitive behaviours significantly increased with sensory hypersensitivity in typically-developing individuals as well. This effect was consistent across all modalities in both autism spectrum disorder and typically developing groups; group differences were observed in the oral and tactile modalities. Furthermore, sensory hypersensitivity was significantly predictive of repetitive behaviours in all participants, autism spectrum disorder and typically-developing, and importantly, autism spectrum disorder diagnosis did not add any predictive influence above and beyond sensory hypersensitivity. Finally, sensory hypersensitivity was significantly predictive of all subdomains of repetitive behaviours, including repetitive motor movements, rigidity and adherence to routine, preoccupation with restricted patterns of interest and unusual sensory interests, and diagnosis added no predictive ability beyond sensory hypersensitivity.