Nano-sized polyhedral crystalline Cu2O was evenly loaded throughout the structure of TiO2 nanotube arrays (TNTs) using an electrodeposition method, which resulted in a nanocomposite namely Cu2O/TNTs. The content of Cu2O loaded on the arrays was controlled by varying the electrodeposition charges. Under visible light, the photocurrent for water splitting and photocatalytic decolorization efficiency of dye Acid orange II (AO-II) of the Cu2O/TNTs obtained with the deposition charges of 500 mC were about 35 and 18 times that of TNTs, respectively. The polyhedral Cu2O/TNTs would be a promising material for solar energy conversion and organic pollutant degradation.