Porous barium strontium titanate−titania (BST−TiO2) nanocomposite was developed by the combination of electrochemical anodization and hydrothermal synthesis. Self organized titania nanotube arrays were first fabricated by electrochemical anodization of titanium foil in 0.2 wt.% HF. The as-anodized titania was then used as a template and was subject to a hydrothermal treatment in the solution mixture of barium hydroxide and strontium hydroxide with different molar ratios. Well crystallized barium strontium titanate was developed directly from the titania nanotubes. Annealing was carried out to transform residual amorphous titania to crystallized anatase, resulting in the porous BST−TiO2 nanocomposite. The surface morphology and structure of the nanocomposite were characterized. The photoelectrochemical response of the BST−TiO2 composite was investigated and the photocatalytic property was evaluated through the photo-decomposition of an organic dye solution. The effect of hydrothermal parameters on the surface morphology and the photocatalytic activity of the nanocomposite was studied.