A series of N-doped graphene (NG) and TiO₂ supported MnO_x–CeO₂ catalysts were prepared by a hydrothermal method. The catalysts with different molar ratios of Mn/Ce (6 : 1, 10 : 1, 15 : 1) were investigated for the low-temperature selective catalytic reduction (SCR) of NO_x with NH₃. The synthesized catalysts were characterized by HRTEM, SEM, XRD, BET, XPS, and NH₃-TPD technologies. The characterization results indicated that manganese and cerium oxide particles dispersed on the surface of the TiO₂–NG support uniformly, and that manganese and cerium oxides existed in different valences on the surface of the TiO₂–NG support. At Mn element loading of 8 wt%, MnO_x–CeO₂(10 : 1)/TiO₂–1%NG displayed superior activity and improved SO₂ resistance. On the basis of the catalyst characterization, excellent catalytic performance and SO₂ tolerance at low temperature were attributed to the high content of manganese with high oxidation valence, extensive oxidation of NO into NO₂ by CeO₂ and strong NO adsorption capacity, and electron transfer of N-doped graphene.