Photogenerated charges were found to involve in activation of peroxydisulfate (PDS) on mesoporous carbon nitride (MCN) with Lewis basic sites under visible light irradiation. Photogenerated hole (h+), superoxide radical (O2·−) and singlet oxygen (1O2) were verified as the most important active species for 2,4,6-trichlorophenol (TCP) removal. Lewis basic sites of MCN induced the interface hydrolysis of PDS to produce hydroperoxyl anions (HOO−) and peroxide ions (O22−), which was further reacted with h+ to generate O2·− and 1O2 predominantly. The efficiently separated electron (e−) was responsible for the nucleophilic attack toward the CCl bond of TCP. Moreover, the electrical energy per order (EEO) of vis/MCN/PDS (3.75 × 106 kW h m−3 order−1) was an order of magnitude lower than that of UV/PDS (3.14 × 107 kW h m−3 order−1). This work highlighted the metal-free MCN with Lewis basic sites as a photocatalyst to activate PDS and elucidated a new strategy of PDS activation for chlorophenol pollutants removal.