Hierarchical flower-like hexagonal molybdenum trioxide (MoO3) film, with a light-driven response, was grown on a wood surface using a one-pot low-temperature hydrothermal method. The crystal structures, microstructure investigations, chemical compositions, and UV-Vis analysis of the MoO3 film on the wood surface were studied. In addition, the growth mechanism of the flower-like MoO3 was put forward. The X-ray diffraction results show that the fabricated MoO3 had a hexagonal structure and the average grain size was 65.6 nm, according to Scherrer's equation. Scanning electron microscopy analysis demonstrated that the hierarchical MoO3 film was composed of many unique bumps that were assembled using numerous microrods. The formation mechanism reveals that during the hydrothermal process the dispersive MoO3 particles first created and then assembled the 3D flower-like structures. The energy dispersive spectrometer, Raman spectrum, and X-ray photoelectron spectroscopy confirmed the MoO3 film grown on the wood surface. The UV-Vis analysis suggested that the as-fabricated product responded well to stimulation from a UV light at 365 nm and exhibited outstanding color changes. The calculated band gap of the MoO3 film based on K-M model was around 2.98 eV.