Although up to 50% of children with Attention-Deficit/Hyperactivity Disorder (ADHD) meet criteria for an anxiety disorder, it is unclear how comorbid anxiety influences social functioning for this population. Understanding the factors associated with social functioning in ADHD is important given the limited efficacy of existing social skills interventions for this population. This systematic review aimed to determine the association between anxiety and social functioning (social problems, peer status, and social skills/ competence) in children and adolescents with ADHD. A standardised search protocol was used, identifying 4807 articles for screening with 31 included in the final review. Anxiety symptom severity was associated with lower levels of social skills and higher levels of social problems in young people with ADHD. However, few differences emerged when defining anxiety based on diagnostic measures. Although the results varied considerably amongst studies, a number of key variables emerged that influenced the associations between anxiety and social functioning including the type of reporter and sample characteristics such as age, sex, ADHD subtype and other mental health comorbidities. These findings have implications for social functioning interventions in ADHD given the role of anxiety symptoms in predicting poorer social functioning.