Experimental and theoretical methods have combined to explore the role of carbon nitride polymer (CNP) in the photocatalytic performance of CNP-sensitized TiO₂ (P25). In this work, CNP rather than its precursors has been used to directly sensitize TiO₂ at 170 °C based on acid–base interaction and the photocatalytic performance of CNP-sensitized TiO₂ is evaluated by degradation of methyl orange under visible light irradiation. The obtained results show the photocatalytic performance of CNP-sensitized TiO₂ is obviously stronger than TiO₂ and CNP. The high performance results not only from transferring the photoinduced electrons from CNP to the conductivity band (CB) of TiO₂ and the increased separation efficiency of photoinduced electrons and holes, but also possibly from hole activation. Hole activation may result from the interaction between TiO₂ and CNP, which increases the oxidation ability of the photoinduced hole that leaves the CNP skeleton after light irradiation.