Unhealthy exercise (UE) is a common symptom of eating disorders (EDs) associated with elevated chronicity and relapse. Previous research suggests that UE serves an emotion regulation function, especially to reduce negative affect. UE may be especially prevalent among individuals with anorexia nervosa (AN), as UE and restrictive eating may be used to avoid unpleasant emotions. It is unclear whether changes in emotion avoidance (EA) can lead to changes in UE over time. The current study examined whether month 1 EA mediated the relation between baseline UE and month 2 UE in a clinical sample of 127 patients (M = 22.52 [SD = 11.75], 92.9% female) recruited from an ED outpatient treatment program. The current study also explored whether this mediation was stronger for individuals with AN than other ED diagnoses. Findings revealed that changes in EA significantly mediated the relation between changes in UE from baseline to month 2 of treatment. ED diagnosis did not moderate this relation. Findings suggest that improvements in EA may reduce UE over time. Treatment should target UE through cultivation of increased emotion acceptance.Level of evidence Level III: evidence obtained from well-designed cohort study.