||To develop damage-tolerant materials, researchers have focused on structural materials in nature. Among them, nacre is one of the most attractive materials. It has macroscopically layer-by-layer structures composed of inorganic platelets and organic matrices with elaborate interactions between them, which lead to exceptional mechanical properties. Motivated from this system, we designed and fabricated microplatelet-reinforced polymer composites (film and bulk form) with uniform layer-by-layer microstructures and superior mechanical properties. To achieve such structures, we propose a novel hydrogel-film casting method that addresses disadvantages of conventional fabrication methods; it is appropriate for preparing composites with various shapes, thicknesses, and sizes. Through combination of inorganic microplatelets and strong stiff organic matrices, an integrated strength, stiffness, and toughness was achieved. The design and fabrication strategies would yield engineering composites.