Hollow polymer nanospheres (HPNSs) have received an increased level of attention, not only for their fundamental scientific interest, but also for technological applications. Despite a great deal of research effort, most of the current HPNSs are suffering from a poor polydispersity as well as a particle size larger than 500 nm. Here, we report the synthesis of highly monodisperse hollow microporous polystyrene nanospheres (MHMPNSs) with diameters as low as 120 nm based on a facile hypercrosslinking strategy. We utilize the rapid formation of an almost unreactive crosslinked polystyrene outer skin during the initial hypercrosslinking process, to minimize the undesired inter-sphere crosslinking. Due to the intra-sphere hypercrosslinking, the resulting MHMPNSs possess a well-developed microporous shell structure. The MHMPNSs are able to be used as potential absorbents toward organic vapors, because of their unique hollow core and microporous shell characteristics.