We report a new approach to the synthesis of uniform, high areal density Pt nanocrystals supported by conducting polymers. The key strategy is the use of ice-templated, two-dimensional polyaniline nanosheets at the air-water interface as a platform for expediting Pt nucleation. Highly crystalline Pt nanoparticles with a narrow size distribution of 2.7 ± 0.3 nm and a high electrochemically active surface area of 94.57 m2 g-1 were obtained. Pt NPs were strongly anchored to the polyaniline nanosheets, and demonstrated high current densities, good durability for the methanol oxidation reaction, and excellent carbon monoxide tolerance, all of which are unprecedented. The idea established in this study could be applied to the production of a wide range of other catalysts with enhanced activities.