The change of photon statistics in the fluorescence of a single CdSe/ZnS core/shell colloidal nanocrystal quantum dot (NQD) accompanying the atomic force microscopy (AFM) manipulation of a cubic Au nanoparticle (AuCube) was investigated to elucidate the effect of plasmonic nanostructures on the multiexciton dynamics of the NQD. Upon coupling to an AuCube of a well-defined size and shape, we directly observed the conversion of a single-photon emission from an individual NQD to a multiphoton emission, and this was accompanied by an increase in fluorescence intensity and a reduction in fluorescence lifetime. The multiphoton emission then returned to a single photon emission upon separating the AuCube from the single NQD. The efficiency of the multiphoton emission was enhanced 6.9 times through the use of the AuCube. The enhancement of the multiphoton emission was attributable mainly to the augmentation of the biexciton emission rate. These results provide evidence that quantum dot photon statistics can be manipulated by plasmonic nanostructures, and NQD-plasmonic nanostructure systems can be desirable for many technological applications.