To construct high-performance aqueous ammonium-ion full batteries, (NH₄)₂V₆O₁₆·1.5H₂O (NVO) nanoribbon cathodes were prepared by pH-regulated hydrothermal synthesis. Anodes were prepared by growing the active material polyaniline (PANI) on carbon cloth. The assembled NVO//PANI full cells exhibit a reversible capacity of 109.5 mA×h/g at a current density of 1.0 A/g and a high energy density of 23 W×h/kg. The ammonium-ion intercalation/extraction mechanism is primarily governed by the pseudocapacitance behavior. These results indicate that NVO is a potential candidate as a cathode material for aqueous ammonium-ion batteries.