Inert　C–H　bonds　activation　at　room　temperature　has　been　regarded　as　the　control　step　in　photocatalytic　generation　of　valuable　products　from　hydrocarbons.　Herein,　lead-free　perovskite　Cs3Bi1.8Sb0.2Br9　nanosheets　with　a　proper　amount　of　Sb　in　Cs3Bi2Br9　not　only　improves　optical　absorption　due　to　anomalous　band　gap　behavior,　but　also　promotes　the　generation　of　holes　(h+).　The　convergence　of　h+　on　the　surface　of　Cs3Bi1.8Sb0.2Br9　is　crucial　for　the　dissociation　of　toluene　C(sp3)–H　bond,　which　was　proved　by　the　density　functional　theory　calculation　and　isotopic　labelling　results.　The　excellent　activity　in　photocatalytic　selective　oxidation　of　toluene　with　a　conversion　rate　of　5.83　mmol　g−1h−1　under　visible　light　is　the　highest　ever　achieved.　This　work　sheds　light　on　the　modification　of　halide　perovskites　through　the　regulation　of　B-site　cations　for　photocatalytic　applications.　©　2021　Elsevier　Ltd