Polymer-tethered nanoparticles with different geometric shapes are very useful fillers of polymer nanocomposites. Herein, a universal approach for the fabrication of such nanoparticles with precisely controlled shape and composition is reported. By microphase separation of poly(3-(triethoxysilyl)propyl methacrylate)-block-polystyrene (PTEPM-b-PS) in the presence of oligomers, o-TEPM (oT) and/or o-S (oS), followed by cross-linking and dispersion in PS solvent, precisely tailored PS-grafted nanoparticles were prepared. These particles include those with varied shapes but identical PS shells, particles with varied core sizes but the same PS shell, and particles with fixed shapes but varied PS shells. These particles are ideal model nanofillers to study the dynamics and reinforced mechanism of polymer nanocomposites.