Background: Autism Spectrum Disorder (ASD) is a pervasive neurodevelopment disorder characterised by impairment in social communication and presence of restricted, repetitive patterns of behaviour, interests, or activities. A growing body of research has shown that children with ASD experience significantly greater anxiety levels than typically developing children. Anxiety disorders have been found to be one of the most prevalent psychiatric comorbidities in this population of children and are associated with debilitating psychosocial impairment. Objective: This study aimed to examine factors associated with anxiety disorders among Chinese children diagnosed with ASD in Hong Kong. Methods: This cross-sectional study was conducted at a child and adolescent psychiatry outpatient clinic from August 2019 to April 2020. The sample consisted of one hundred thirty-two subjects aged 6 to <12 years who had a diagnosis of ASD. Structured interviews and questionnaires including the Diagnostic Interview Schedule for Children, Parenting Stress Index-Short Form, Parenting Styles and Dimensions Questionnaire and a socio-demographic questionnaire were administered for the assessment of anxiety disorders and their associated factors. Results: Greater qualitative deficits in reciprocal social interaction skills, attention-deficit/hyperactivity disorder and maternal mood disorder were found to be significantly associated with anxiety disorders in children with ASD. Conclusion: Anxiety disorders are prevalent among children with ASD. Early recognition and identification of comorbid anxiety disorders are necessary in the diagnostic process of ASD. This study enriches our understanding of the factors associated with anxiety disorders in this population of children. For future research directions, furthering our understanding on the aetiological pathways, course of illness, and outcome of anxiety disorders in autistic children is highly warranted.