The surface charge of various anionic unilamellar nanosheets such as graphene oxide (GO), Ti0.87O20.52- and Ca2Nb3O10- nanosheets, has been successfully modified to be positive by interaction with polycations while maintaining a monodisperse state. A dilute anionic nanosheet suspension was slowly added dropwise into an aqueous solution of high-molecular-weight polycations, which attach on the surface of the anionic nanosheets via electrostatic interaction. Surface modification and transformation to positively charged nanosheets were confirmed by various characterizations including AFM and zeta potential measurements. Because the sizes of the polycations used are much larger than the nanosheets, the polymer chains may run off the nanosheet edges and fold to the fronts of the nanosheets, which could be a reason for the continued dispersion of the modified nanosheets in the suspension. By slowly adding a suspension of polycation-modified nanosheets and pristine anionic nanosheet dropwise into water under suitable conditions, a superlatticelike heteroassembly can be readily produced. Characterizations including transmission electron microscopy and X-ray diffraction provide evidence the formation of the alternately stacked structures. This approach enables the combination of various pair of anionic nanosheets with different functionalities, providing a new opportunity for the creation of unique bulk-scale functional materials and their applications.