Polypyrrole (PPy)/CuBi₂O₄ nanosheets (NSs) were prepared by an in situ polymerization process and the NS-modified glassy carbon electrode (GCE) for electrochemical determination of benzoic acid was studied. The structure, morphology, and functional groups of the PPy/CuBi₂O₄-NSs were analyzed by X-ray diffraction, transmission electron microscopy (TEM), high-resolution TEM, and Fourier transform infrared spectroscopy. The obtained NSs contain a tetragonal CuBi₂O₄ phase, and nanoscale PPy particles attach to the surface of the NSs. The electrochemical responses of the PPy/CuBi₂O₄-NS-modified GCE in 0.1 M KCl solution with benzoic acid were investigated by the cyclic voltammetry (CV) and electrochemical impedance spectroscopy. An irreversible CV peak is located at −0.84 V on the PPy/CuBi₂O₄-NS-modified GCE in 2 mM benzoic acid and 0.1 M KCl solution. The intensities of the CV peaks show linear variation with increasing the scan rate and concentration of benzoic acid. The linear range is 0.001−2 mM with a detection limit of 0.52 μM. The PPy/CuBi₂O₄-NS-modified GCE shows high stability and reproducibility. The prepared PPy/CuBi₂O₄-NSs have great promise in the electrochemical detection of benzoic acid.