Abstract Objective To evaluate the efficacy and safety of fremanezumab for migraine prevention. Design Retrospective, single-center, real-world study. Setting Regional tertiary headache center in Japan. Subjects Adult individuals with migraine (n = 165, male = 17, female = 148; average age = 45.5 ± 16.0 years) who received fremanezumab between September 2021 and August 2022. Methods Fremanezumab was administered subcutaneously at a monthly dose of 225 mg or quarterly dose of 675 mg based on patient preferences. Patients received fremanezumab treatment for up to 1 year unless it was discontinued. Monthly data were collected on migraine days, headache days, and days requiring acute medication. Results Of the 165 patients, 125 (75.7%) received fremanezumab as their first anti-calcitonin gene-related peptide-related antibody drug. Significant reductions in monthly migraine days, headache days, and days requiring acute medication were observed in those with episodic and chronic migraines. The baseline monthly headache days was 8.1 ± 4.0 in the episodic migraine group, which reduced to 6.1 ± 4.8, 5.8 ± 4.4, 4.7 ± 3.6, and 4.6 ± 3.3 days at 1, 3, 6, and 12 months, respectively; in the chronic migraine group, the baseline monthly headache days was 20.9 ± 6.1, which reduced to 17.0 ± 8.9, 15.0 ± 9.2, 13.0 ± 7.7, and 12.0 ± 9.1 days at 1, 3, 6, and 12 months, respectively. Treatment benefits were enhanced after 6 months of administering fremanezumab in the chronic migraine group. Conclusions In this real-world study of patients with migraine, fremanezumab appears to be effective and safe. Further studies are required to identify additional predictors of treatment success and failure with fremanezumab.