An integrated substrate, an electronic assembly, and manufacturing methods thereof are provided. The integrated substrate structure includes a coarse redistribution structure, fine redistribution segments, and conductive connectors. The coarse redistribution structure includes a coarse dielectric layer and a coarse circuitry embedded therein. The fine redistribution segments disposed over the coarse redistribution structure and disposed side by side and apart from one another. The respective fine redistribution segment includes a fine dielectric layer thinner than the coarse dielectric layer, and a fine circuitry embedded in the fine dielectric layer. The fine circuitry includes a dimension and a pitch finer than those of the coarse circuitry, and a layout density of the fine circuitry is denser than that of the coarse circuitry. The conductive connectors are interposed between the coarse redistribution structure and the fine redistribution segments, and the coarse circuitry is electrically coupled to the fine circuitry through the conductive connectors.