Bimekizumab, an interleukin (IL)-17A/IL-17F inhibitor, is effective for moderate-to-severe psoriasis. However, long-term maintenance of early treatment outcomes is not examined in real-world settings, with no analyses stratified by dosing intervals (every 4 weeks [Q4W] vs. 8 weeks [Q8W]) or histories of biologics (bio-naïve vs. bio-switched). We investigated whether the outcomes achieved at week 16 of bimekizumab treatment may be maintained until week 52, stratified by dosing intervals or histories of biologics. This prospective study included 63 Japanese patients (≥15 years) with moderate-to-severe psoriasis. All the patients received bimekizumab 320 mg Q4W until week 16, thereafter Q4W or Q8W. We evaluated the maintenance rates until week 52 for Psoriasis Area and Severity Index (PASI) 75, PASI 90, PASI 100, absolute PASI ≤2, absolute PASI ≤1, Static Physician's Global Assessment (sPGA) 0/1, or Dermatology Life Quality Index (DLQI) 0/1 achieved at week 16, stratified by dosing intervals or histories of biologics. In total patients, the maintenance rates for PASI 75, absolute PASI ≤2 or ≤1, or sPGA 0/1 were mostly 100% until week 52 while those for DLQI 0/1 decreased to around 80%, irrespective of dosing intervals or biologic histories. The maintenance rates for PASI 90 and 100 were mostly 100% in the Q4W group and bio-naïve patients in the Q8W group while both decreased to 71.4% at week 52 in bio-switched patients in the Q8W group. This study showed that the improvement of skin lesions at week 16 of bimekizumab treatment can be almost completely maintained until week 52.