Disclosed herein are isolated humanized monoclonal antibodies that specifically bind Japanese encephalitis virus (JEV) with a binding affinity of about 1.0 nM or less. Nucleic acids encoding these antibodies, expression vectors including these nucleic acid molecules, and isolated host cells that express the nucleic acid molecules are also disclosed. Methods of treating, preventing, and/or ameliorating JEV infection in a subject with JEV also are disclosed. Additionally, the antibodies can be used to detect JEV in a sample, and methods of diagnosing JEV infection, or confirming a diagnosis of JEV infection in a subject, are disclosed herein that utilize these antibodies.