The current study explored interactions between emotion regulation (ER) and cognitive-behavioral flexibility in everyday life in individuals with anorexia nervosa (AN). Participants were 97 female adults with current (57%) or past (43%) full or partial AN syndrome diagnosis. Participants completed the Difficulties with Emotion Regulation Scale, Emotion Regulation Questionnaire, Eating Disorder Flexibility Index, Eating Disorder Examination Questionnaire and Depression Anxiety Stress Scale short form. Lower flexibility was a strong independent predictor of more severe ED-related cognitions and higher frequency of compensatory behaviors beyond individual differences in emotion regulation and mood. ER measures did not predict clinical characteristics. However, two interactions between flexibility and ER measures were observed which suggested there was a stronger association between greater flexibility and higher BMI for individuals with either higher levels of cognitive reappraisal use, or higher levels of global ER difficulties. Interactions between flexibility and emotion regulation provide evidence that co-occurring difficulties may impact clinical outcomes in AN.