Erection of a resourceful p-n heterojunction is a state-of-the-art tactic to flourish the charge anti-recombination process at the heterojunction interface and boost the photocatalytic activities under visible light irradiation. In the present work, we have engineered a new series of PbTiO3/LaCrO3 (PT/LC) p-n heterojunction through a facile two-step combustion process. The structural, interface, and optical analysis distinctly revealed a strong intact between p-type LaCrO3 and n-type PbTiO3, elucidating their electronic channelization and substantial reduction of electron hole recombination at the PbTiO3/LaCrO3 interface, which extend the lifetime and population of photogenerated charges in the p-n heterojunction material. The asymmetry photocurrent in the opposite directions and an inverted characteristic V-shape Mott-Schottky plot of the optimal PT/LC (7/3) material demonstrated the construction of a p-n heterojunction. The optimal p-n heterojunction possesses excellent photo stability, and it revealed the highest photocatalytic activity toward degradation of phenol, that is, 86% and hydrogen generation, that is, 343.57 mu mol in 2 h. The enhanced photocatalytic activities of the p-n heterojunction materials in comparison to pristine ones are due to the higher separation charge carriers across the p-n heterojunction interface, which was deeply elucidated by carrying out electrochemical impedance spectroscopy, time-resolved photoluminescence spectroscopy, and photoluminescence analyses. These materials pave a new way to design the interface intact photocatalyst with an ultrafast approach for migration of photoexcited electrons across the p-n heterojunction and enhance the photocatalytic activities.