Photocatalytic H2 evolution is regarded as an ideal approach to produce green energy. Here, a step‐scheme (S‐scheme) heterojunction of macro/mesoporous TiO2/g‐C3N4 photocatalysts with enhanced H2 evolution performance is constructed via a simple chemical vapor deposition process. It is found that the microstructure of samples can be easily controlled by adjusting the dosage of melamine. As compared to the respective monocomponent TiO2 and g‐C3N4, the H2 evolution rate of TiO2/g‐C3N4 S‐scheme heterojunction is greatly improved. The H2 evolution rate of the 20CT sample reaches the maximum value of 3211 μmol g−1 h−1, which is much higher than those of TiO2 and g‐C3N4 by factors of 27.2 and 7.5, respectively. In addition, through in‐depth analysis with photoluminescence, X‐ray photoelectron spectroscopy, and Mott–Schottky characterizations, a new mechanism of S‐scheme heterojunction is proposed for the obtained system. The formation of the S‐scheme heterojunction in TiO2/g‐C3N4 is therefore responsible for the observed photocatalytic performance enhancement, due to the efficient charge separation as well as the high redox ability.