Introduction: The aim of this systematic review was to synthesize the literature on the correlates and risk factors of anxiety among adults with ID. Methods: Following the PRISMA guidelines, a systematic search of peer-reviewed literature was conducted across six major electronic databases. From an initial screening of 844 records, 13 studies were included for full-text review. Factors associated with anxiety were categorized utilizing the biopsychosocial model. Methodological quality was evaluated. Results: Correlates of anxiety were identified at all levels of the biopsychosocial model, including psychological or psychiatric diagnoses, level of ID, gender, chronic health conditions, stressful life events, and social interactions. Modifiable correlates were discussed as potential targets for designing anxiety interventions for adults with ID. Conclusion: Despite the increased recognition of the mental health needs of individuals with ID in recent years, this review highlighted a dearth of research investigating the risk factors of anxiety among this population.