Objective: this post hoc analysis aimed to evaluate the efficacy of fremanezumab in difficult-to-treat chronic migraine (CM) patients with and without psychiatric comorbidities (PCs), mainly anxiety and/or depression. Methods: We assessed data from CM patients with and without PCs who failed at least 3 preventives and eventually received at least 3 consecutive monthly doses of fremanezumab 225 mg. Outcomes included the crude response (≥50% reduction in monthly headache days (MHDs)) rates to fremanezumab from the baseline to the last clinical follow-up. The changes in MHDs; MHDs of moderate/greater severity; monthly days with intake of abortive medication; and the proportion of patients’ changing status from with PCs to decreased/without PCs were also compared. Disability and quality of life (QOL) outcomes were also assessed. Results: Of 107 patients enrolled, 65 (60.7%) had baseline PCs. The percentage of patients with (n= 38/65; 58.5%) and without (n= 28/42; 66.6%) PCs that achieved a ≥50% reduction in MHDs with fremanezumab was comparable (p= 0.41), whereas MHDs were significantly reduced (difference vs. baseline) in both patients with PCs (mean −8.9 (standard error: 6.8);p< 0.001) and without PCs (−9.8 (7.5);p< 0.001). Both groups experienced significant improvements in all other efficacy, disability, and QOL outcomes at comparable rates, including in MHD reduction. A significant proportion of fremanezumab-treated patients with baseline PCs de-escalated in corresponding severities or even reverted to no PCs (28/65; 43.1%) post-fremanezumab. Conclusions: fremanezumab appears to be effective as a preventive treatment in difficult-to-treat CM patients with and without PCs while also being beneficial in reducing the severity of comorbid anxiety and/or depression.