Catalytic oxidation using manganese corrole is a hot topic of contemporary porphyrin chemistry, in which PhIO, TBHP, PhI(OAc)₂, KHSO₅ and m-CPBA are usually used as oxidants. This article reports the first selective oxidation of styrene to benzaldehyde using a manganese(III) corrole catalyst and sodium nitrite (NaNO₂) as oxidant and cocatalyst at room temperature. The yield was 158.1% in air and 96.5% under a nitrogen atmosphere, showing oxygen might be involved in the reaction and that NaNO₂ is an oxygen source and cocatalyst in the system. The peripheral electron-withdrawing substituents of the manganese corrole were favorable to the catalytic reaction. Radical inhibition and H₂¹⁸O experiments proved that the catalytic reaction was a free radical and hydrolysis-involved reaction.