Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory disease of the central nervous system that can lead to devastating neurological disabilities such as blindness and impaired mobility. Given that NMOSD can cause severe neurological deteriorations even with a single episode, exploring effective relapse prevention strategies in NMOSD is imperative. Recently, various biological monoclonal antibody therapies targeting diverse mechanisms have shown efficacy in preventing relapses in NMOSD, as evidenced by clinical trials. These monoclonal antibody therapies include complement inhibition (eculizumab and ravulizumab), B-cell depletion (rituximab and inebilizumab), and interleukin-6 receptor blockade (tocilizumab and satralizumab) mechanisms. Some of these therapies are now reimbursable, and this review summarizes their mechanisms, administration methods, reimbursement status in Korea, efficacy, and safety profiles in clinical practice.