p-Nitrophenol (PNP) is a difficultly decomposed organic pollutant under solar light in the absence of strong oxidants. This study shows that under artificial solar light PNP can be effectively degraded by a Cu₂O/TiO₂ p-n junction network which is fabricated by anodizing Cu⁰ particles-loaded TiO₂ nanotubes (NTs). The network is composed of p-type Cu₂O nanowires on the top surface and Cu₂O nanoparticles on the inner walls of the n-type TiO₂ NT arrays. The Cu₂O/TiO₂ network shows much higher degradation rate (1.97 μg/min cm²) than the unmodified TiO₂ NTs (0.85 μg/min cm²). The enhanced photocatalytic acitivity can be attributed to the extended absorption in the visible resulting from the Cu₂O nanowire networks and the effective separation of photogenerated carriers driven by the photoinduced potential difference generated at the Cu₂O/TiO₂ p-n junction interface.