Anxiety comorbidity is quite common in children with attention-deficit hyperactivity disorder (ADHD). What is known about the relationship between anxiety, attachment and emotion regulation in such children is still limited. We aimed to investigate the associations between attachment, emotion regulation and comorbid anxiety in children with ADHD. 100 children with ADHD and 100 children without any diagnosis aged 8-13 years were included. After the participants were clinically evaluated, Turgay ADHD Scale, Emotion Regulation Checklist, Revised Child Anxiety and Depression Scale-Child Version (RCADS-CV) and Kerns' Security Scale were completed. According to the RCADS-CV scores, ADHD/ANX(+), ADHD/ANX(-), and control groups were formed. The emotional lability/negativity levels were higher in the ADHD groups compared to the non-ADHD controls. Paternal and maternal attachment security levels were lower in the ADHD/ANX(+) group compared to the controls. The regression analysis indicated that higher hyperactivity/impulsivity symptom levels and lower maternal attachment quality were associated with higher anxiety in children with ADHD. These results suggest that focusing on attachment quality and emotion regulation problems may be significant in management of core symptoms and comorbid anxiety problems in children with ADHD.