In this work, we report a bismuth oxide film electrode with oxygen defects and honeycomb multilevel structure prepared by one-step hydrothermal method. The control of raw materials enables to control the thickness and morphology of BiO electrodes. The photoelectrocatalytic of prepared electrodes were tested in various conditions. Under visible light irradiation (λ ≥ 420 nm) and 3 V bias, the sample BiO-2 has the highest photoelectrocatalytic activity, which is 4.95 times higher than the photocatalytic activity and 9.86 times higher than the electrocatalytic activity. The oxygen defects of bismuth oxide were confirmed by EPR and DFT calculation. The morphology and structure of prepared samples were tested by XRD, scanning electronic microscope (SEM), high-resolution transmission electron microscope (HRTEM) and X-ray photoelectron spectroscopy (XPS). The enhanced photoelectrocatalytic activity is attributed to the proper bias voltage, oxygen defects, and honeycomb multilevel structure. The results of tapping experiments showed that the main active species during the photoelectrocatalytic progress is superoxide radical and the mechanism of the photoelectrocatalysis was proposed.