Crystal orientation of two-dimensional (2D) butylammonium lead iodide perovskite as a light absorber of solar cells was controlled by use of oriented TiO2 nanowire (TNW) array as a scaffold of crystallization. Tuning crystallization conditions in spin-coating on TNW array, the highest conversion efficiency of the 2D perovskite-based solar cell was obtained with a vertically oriented film of perovskite embedded in the TNW array.