A novel low-cost and highly efficient hydrazine sensor based on nitrogen-doped carbon nanopolyhedra (CNP), Prussian blue (PB) and conductive polymer is synthesized. CNP containing cobalt, which were prepared via pyrolysis of the Zeolitic Imidazole Framework-67 (ZIF-67), are found to be catalytically active for the synthesis of PB. Polypyrrole (PPy) is then coated on the PB/CNP composite to provide high conductivity and an environmental stability of the PB/CNP/PPy compound. The as-prepared electrode was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and electrochemical methods. The electrode modified with PB/CNP/PPy exhibits an excellent activity for the electrocatalytic oxidation of hydrazine. It demonstrated a rapid response of less 2 s, a sensitivity of 0.22 A M−1, a long linear range from 7.5 × 10−7 M to 1.7 × 10−3 M and a low detection limit (S/N = 3) of 2.9 × 10−7 M, as well as a remarkable stability and selectivity.