Purpose of Review: Monoclonal antibodies against calcitonin gene-related peptide (CGRP) or its receptor have become part of the standard treatment for migraine in clinical practice. The current review focuses on the clinical evidence of CGRP monoclonal antibodies in patients with chronic migraine (CM), including more challenging cases. Recent Findings: CGRP monoclonal antibodies were more effective than placebo in reducing the number of monthly migraine days (MMDs), and the change relative to placebo in the treatment group was between − 1.2 and − 2.7 days at 3 months. CGRP monoclonal antibodies resulted in ≥ 50% response in 27.5 to 61.4% of patients, and doubled the odds for having ≥ 50% response. The findings were generally consistent in patients with coexisting medication overuse or with treatment failures to multiple preventive medications, including onabotulinumtoxinA. The results from real-world studies (RWS) were similar to those seen in clinical trials, and the changes from baseline in the number of MMDs and the response rates largely fell within the ranges of those reported in the treatment group in pivotal trials. The therapeutic effects typically started within a few days, and remained steady after regular treatment for up to 1 year. These agents were generally well tolerated, and the discontinuation rates due to adverse events in clinical trials and in many RWS were < 4.5%. Summary: CGRP monoclonal antibodies are effective and safe in the treatment of patients with CM, including clinical challenging cases. However, the role of CGRP monoclonal antibodies in a number of conditions, such as cardiovascular or cerebrovascular diseases, pregnancy, and overuse of opioids or barbiturates, needs to be further clarified.