In this work, we fabricate a highly effective catalyst for carbon monoxide oxidation based on gold-loaded mesoporous maghemite nanoflakes which exhibit nearly 100% CO conversion and a very high specific activity of 8.41 molCO gAu-1 h-1 at room temperature. Such excellent catalytic activity is promoted by the synergistic cooperation of their high surface area, large pore volume, and mesoporous structure.