Combining the functionality of nanoparticles (NPs) with the processability of polymers offers great promise for designing novel materials. In particular, NPs with tailored surface properties can effectively modify the interface between two distinct fluids and/or different polymer matrices which allows them to function as efficient surfactants. The efficiency of NP surfactants is strongly affected by their size and shape, which influences their adsorption energy to the interface, and the entropic contribution to the system. In this review, the assembly of size-and shape-controlled inorganic NPs at the interface of block copolymers (BCPs) and polymer blends has been focused. First, we discuss the design of size-and shape-controlled NP surfactants and we review the examples of NP surfactant-driven BCPs and polymer blend morphologies. In addition, we review the recent investigations of the morphological transition of BCP emulsion particles induced by NP surfactants.