Metallic nanohole arrays exciting both surface plasmon polariton (SPP) and localized surface plasmon resonance (LSPR) in a single thin film have sparked considerable interest in the field of plasmonics. To exert their full potential for the generation of hot electrons in visible light, we bury an Au nanohole array (AuNHA) under a thin TiO2 layer and decorate Pt nanoparticles randomly on the surface to form the Pt/TiO2/AuNHA nanocomposite. As compared to the Pt/TiO2/Au film, the Pt/TiO2/AuNHA sample with a 90 nm hole diameter shows an enhancement of 4.1 folds in photocurrent density, 14.7 folds in the peak of incident photon-to-current conversion efficiency, and 9.4 folds in the degradation of methyl orange. Moreover, numerical simulations are conducted to analyze the contributions of SPP and LSPR effects at different wavelengths. This work is the first study of AuNHAs fully covered by a thin TiO2 film and provides a unique design of photoelectrodes for solar photocatalysis applications.