Background We evaluated the effect of erenumab, a fully human monoclonal antibody that inhibits the canonical calcitonin gene-related peptide receptor, on migraine-related disability, impact, and health-related quality of life among patients with episodic migraine. Methods Patients enrolled in a phase 3, 6-month, double-blind, placebo-controlled study of once-monthly erenumab 70 and 140 mg for migraine prevention (STRIVE) used an eDiary during the baseline and double-blind treatment phases to complete validated, specific questionnaires, including the modified (monthly) Migraine Disability Assessment Questionnaire; Headache Impact Test; and Migraine-Specific Quality of Life Questionnaire-role function-restrictive (MSQ-RFR), -role function-preventive (MSQ-RFP), and -emotional function (MSQ-EF). Results A total of 955 patients were randomized to receive erenumab 70 mg (n = 317), erenumab 140 mg (n = 319), or placebo (n = 319). Erenumab versus placebo resulted in significantly greater improvements in all patient-reported outcomes; changes from baseline were numerically higher with 140 mg erenumab. Improvements occurred rapidly and were maintained over 6 months of treatment. Between-group differences from placebo over months 4–6 for the 70- and 140-mg dose groups were, respectively, −2.1 and −2.8 for modified (monthly) Migraine Disability Assessment Questionnaire, −2.1 and −2.3 for Headache Impact Test, 5.1 and 6.5 for MSQ-RFR, 4.2 and 5.4 for MSQ-RFP, and 5.2 and 6.7 for MSQ-EF (p < 0.001 for all). Erenumab also significantly reduced the proportion of patients with severe and very severe migraine-related disability and increased the proportion of patients with clinically meaningful improvements in migraine-related impact and health-related quality of life. Conclusion Erenumab reduced migraine disability and impact and improved patients’ health-related quality of life, reinforcing its role as a promising new therapy for migraine prevention.