Porous carbon materials are of great importance for many applications such as energy storage, catalysis, and adsorption. Rational design and low-cost synthesis of carbon structures that can simultaneously offer high surface area and rapid ion/molecule transport properties remain desired for target functions. Here, we report a cost-effective and scalable synthesis of high surface area, size-uniform microporous carbon nanoparticles. A combination of using rigid polymer nanoparticles as the precursor, precarbonization, and activation process leads to carbon nanoparticles with a high surface area (up to 2789 m2 g–1), a large pore volume (up to 1.85 cm3 g–1), and a high packing density (0.5 g cm–3), which is due to the existence of a large amount of highly accessible micropores. Such a unique carbon structure exhibits not only large capacity but also rapid adsorption for both ions and small molecules, demonstrated in high-performance supercapacitors and as an efficient sorbent for removal of pollutants from water. This study provides a new strategy that can be used to further design and tune nanostructured carbon and composite particles to explore many other applications.