Background Erenumab is a calcitonin gene-related peptide (CGRP)-receptor antibody inhibiting CGRP function. CGRP is prominently involved in the pathophysiology of migraine through nociceptive modulation in the trigeminovascular system. This study aims to explore the treatment effect of erenumab in a real-life setting. Methods In this retrospective observational study, we analyzed the data of 91 patients with migraine receiving at least three consecutive monthly injections of erenumab and followed up for 3–12 months. The primary objective was to describe the reduction in monthly migraine days throughout the follow-up period. To identify patients who responded to treatment, we analyzed the association between different patient characteristics and their treatment outcomes. Results Seventy-three patients (80.2%) responded to erenumab treatment, defined as ≥50% reduction of migraine days per month, across all migraine types. It was noted that ethnicity (p-value = 0.015) and older age (p-value = 0.035) were associated with clinically relevant improvement of symptoms. Middle Eastern ethnicity was related to less improvement of symptoms while Europeans were more likely to benefit from erenumab therapy (odds ratio: 12.788, p = 0.037). Patients aged from 31 to 40 and 41–65 years benefited most from erenumab treatment with a response rate of 77.8 and 89.9%, respectively, also confirmed by logistic regression (p = 0.047). Neither gender nor dose increase of erenumab showed association with the reported clinically relevant improvement of the symptoms. An association between clinically relevant improvement of headaches and the type of migraine was also noted. Around 87.9% of patients with episodic migraine responded to treatment, followed by 84.1% of chronic migraine patients and 50% of medication overuse headache patients. Medication overuse headache showed a lower probability of therapy success with erenumab (odds ratio: 0.126, p = 0.039). An improvement of headaches was eminent in patients who received 140 mg erenumab monthly (2 × 70 mg injections) and patients who had one injection every two weeks. Conclusions Erenumab is a novel preventive treatment for all migraine types. Clinically relevant improvement of headaches and reduction of monthly migraine days were demonstrated in patients that continued the treatment course. In real-life, a substantial number of patients suspended therapy early, reasons for which need further investigation.