This study examined the influence of parental cognition, including attitudes, beliefs, and understanding of anxiety, on emotion dysregulation in children with anxiety disorder. A total of 47 clinically anxious children (6–17 years old) and their parents were involved in the current study. The mothers and fathers separately completed a self-reported questionnaire assessing their attitudes, beliefs, and understanding of their children’s anxiety, while the children completed a self-report questionnaire assessing emotion dysregulation. Pearson correlation and hierarchical regression analyses were used for data analysis. The results indicated that only fathers’ higher levels of unhelpful attitudes, beliefs, and understanding of anxiety were positively and significantly associated with greater emotion regulation (ER) difficulties in anxious children. Furthermore, fathers’ unhelpful cognitions regarding anxiety uniquely predicted their children’s emotion regulation difficulties. These findings highlight the importance of including fathers in preventive and therapeutic interventions in promoting ER abilities in children with anxiety disorder.