Ordered mesoporous NiSiAl composite oxides with an amorphous phase were prepared by an improved evaporation-induced self-assembly strategy. The silica was distributed homogeneously in the mesoporous skeleton and improved the ordered mesoporous structure of NiAl. Catalytic tests toward the CO₂ reforming of CH₄ indicated that the NiSiAl exhibited higher catalytic activity and stability over 100 h at 700 °C than NiAl. The enhanced performance results from the high thermal stability induced by Si doping, which hinders the Al₂O₃ phase transformation from amorphous to -Al₂O₃; therefore, the uniform dispersion of the Ni nanoparticles is retained owing to the confinement effect of the ordered mesopores. The stabilized Ni nanoparticles reinforced the resistance of the catalyst to carbon deposition and, thus, boosted its durability. Notably, even under more stringent conditions (750 °C, 200 h), NiSiAl-0.10 retained its amorphous Al₂O₃ structure and showed outstanding durability, almost without any deactivation.