Abstract To date, the pursuit of dual-meospores while maintaining definite dispersity and small particle size of mesoporous carbon nanospheres (MCN) still remains a great challenge, due to the aggregation tendency of small particles (especially below 200 nm) and the destruction of nanospherical structure after excessively creating mesopores. Herein, we report a high acid induced heterogeneous nucleation and growth approach to synthesize dual-mesoporous carbon nanospheres (DMCN) with well-controlled small diameters. This highly acidic driven method has effectively balanced the organic-organic, organic-inorganic and inorganic-inorganic assembly to control the polymerization kinetics, thus forming dispersed nanospheres. The surface incompatibility issues between silica nanoparticle (SN, the inorganics) and resorcinol/formaldehyde (RF, the organisms) were addressed through the employment of inorganic/ionic/organic interaction to synthesize DMCN under highly acidic condition. An extended I + X − S + mechanism is proposed to interpret this formation process. By precisely controlling the processes of growth and cooperation-assembly, the diameter can be easily manipulated over a wide range (130–60 nm), which is a facile route for preparing dispersed small-size DMCN. Meanwhile, a linear function model is established to quantitatively control and predict the particle size. Since the DMCN integrated both the advantages of small diameter (nanosize effect) and bimodal mesopore system (reduction of transport limitation) in one single unit, it exhibits an excellent performance in the release of poorly water-soluble drug and the adsorption of dye molecules.