The development of metal oxide‐based electron transport layers in perovskite solar cells (PSCs) has received intensive research interest for achieving high‐efficiency PSCs. Herein, TiO2nanorods (TiO2NRs) are grown onTiO2seed layers coated on fluorine‐doped tin oxide (FTO) glass substrate by using a hydrothermal method and then are utilized as the electronic transport layer in PSCs. The main concern, after hydrothermal growth of TiO2NRs, is that their crystallinity can be improved by a sequential high‐temperature treatment at 450 °C. In addition to high‐temperature annealing, a low‐temperature treatment with boiling water, which is expected to clean the surface of the TiO2NRs, is developed. In this contribution, the champion PSCs are those based on TiO2NRs where boiling water treatment achieves a maximum power conversion efficiency (PCE) of 15.50%, whereas a PCE of 12.91% is obtained from PSCs based on TiO2NRs with high‐temperature annealing. The remarkable ease of using a water‐assisted process offers an efficient approach to the removal of residuals adsorbed on the surface and circumvents the disadvantage of a thermal annealing method resulting in high‐production costs. This low‐temperature treatment can be used to improve TiO2films in flexible PSCs. After hydrothermal growth of well‐aligned TiO2nanorods, a low‐temperature treatment with boiling water is proven to utilize surface quality of the TiO2nanorods. This water‐assisted treatment is a promising process for use in the TiO2synthesis that can be applied for fabrication as an electronic transport layer in planar perovskite solar cells.