Aims: We aimed to verify the efficacy and safety of tacrolimus as long-term immunotherapy for the treatment of neuronal surface antibody-mediated autoimmune encephalitis (AE) during the first attack. Methods: In this retrospective observational cohort study, patients with neuronal surface antibody-mediated AE who experienced the first attack were enrolled. We compared the outcomes of 17 patients who received tacrolimus with those of 47 patients treated without tacrolimus. Patients were assessed at onset and 3, 6, and 12 months, as well as at the last follow-up, by using the modified Rankin scale (mRS) and the Clinical Assessment Scale in Autoimmune Encephalitis (CASE). The efficacy of tacrolimus was also compared in a subgroup of patients with anti-NMDA receptor encephalitis. Results: Among all patients with neuronal surface antibody-mediated AE, those receiving tacrolimus had lower median mRS scores [1 (IQR = 0-1) versus 2 (IQR = 1-3) in controls, p = 0.001)], CASE scores [2 (IQR = 1-3) versus 3 (IQR = 2-7), p = 0.006], and more favorable mRS scores (94.1% versus 68.1%, p = 0.03) at the 3-month follow-up. No difference was found at the last follow-up. There was no significant difference in the occurrence of relapse and adverse events between the two groups (11.8% versus 14.9%, p = 0.75). In the subgroup of patients with anti-NMDA receptor encephalitis, patients treated with tacrolimus had a lower median mRS score at the 3-month follow-up [1 (IQR = 0-2) versus 2 (IQR = 1-3), p = 0.03]; however, no difference in the outcome was detected at the last follow-up. Conclusion: Tacrolimus can be used as long-term immunotherapy in patients with neuronal surface antibody-mediated AE during the first attack. Treatment with tacrolimus appears to accelerate the clinical improvement of neuronal surface antibody-mediated AE.