In this work, the morphology of TiO₂ nanotubes with small nanowires directly formed on top (designated as TTW) was treated by the method of wet-chemical reaction (WCR) with an alkaline solution. This method was designed to change the surface morphology and chemical activity of the material, thus improving its UV-visible (UV-vis) light absorption and photoelectrochemical (PEC) performance. We explored different alkaline reagents and different processing times to treat the TTW. After treatment by the WCR method with ammonia water (NH₃·H₂O), it was found that a hybrid nanostructure of a thinner wall TiO₂ nanotube array at the bottom and a nanowire porous film on the top (designated as TTWPF), was obtained. The wires are formed by chemical dissolution of the oxide on the top, and there is no grain boundary between the tubes and wires in TTWPF. So, it can make full use of the advantages of nanotubes and nanowires. For one thing, the nanowire porous film on the top can fully utilize the characteristics of both a large specific surface and a high activity in the generation of electron–hole pairs, and the thinner wall nanotube array at the bottom can provide more direct pathways for photogenerated electron transfer. Also, the nanowire porous film can recycle the light scattered by the three-dimensional topography of the highly ordered nanotube array. Meanwhile, the TTWPF exposes more {001} facets of high energy, which have substantial effects on the surface separation and the transportation of photogenerated electron–hole pairs. The data of the PEC performance indicate that the photocurrent density of the bare TTW when treated by the method of WCR with NH₃·H₂O can be increased by up to 238%.