Background While growing evidence suggests the efficacy of various behavioral approaches to the preventive treatment of migraine, it remains largely unclear which behavioral interventions are indicated for which type of patient. This exploratory study aimed to identify moderators for the outcome between migraine-specific cognitive-behavioral therapy and relaxation training. Methods In this secondary analysis of an open-label randomized controlled trial, the data of N = 77 adults (completer sample) with migraine (mean age = 47.4, SD = 12.2, 88% female), who were allocated to either migraine-specific cognitive-behavioral therapy or relaxation training, was examined. Outcome was the frequency of headache days at the 12-month follow-up. We analyzed baseline demographic or clinical characteristics and headache-specific variables (disability, emotional distress, trigger sensitivity and avoidance, pain acceptance, self-efficacy) as candidate moderators. Results Higher headache-related disability (assessed via the Headache Impact Test, HIT-6, B = –0.41 [95% CI: –0.85 to –0.10], p = .047), higher anxiety (assessed via the subscale Anxiety of the Depression, Anxiety and Stress scales, DASS-A, B = –0.66 [95% CI: –1.27 to –0.02], p = .056), and the presence of a comorbid mental disorder ( B = –4.98, [95% CI: –9.42 to –0.29], p = .053), moderated the outcome in favor of migraine-specific cognitive-behavioral therapy. Conclusion Our findings contribute to an individualized treatment selection and suggest that preference for complex behavioral treatment (migraine-specific cognitive-behavioral therapy) should be given to patients with high headache-related disability, increased anxiety, or a comorbid mental disorder. Study Registration: Original study registered in the German Clinical Trials Register ( https://drks.de/search/de ; DRKS-ID: DRKS00011111).