In this work, we report an acoustic agitation approach to enhance the flow of yield stress fluids during inverted projection stereolithography (SLA) 3D printing. The enhanced flow resulted in a reduction of “over-curing” of previously printed layers, with the overall effect of higher resolution printing during inverted SLA. To elucidate the mechanism of the enhanced flow, we numerically simulated the acousto-mechanical coupling in the SLA resin feed system at different agitation frequencies. From the simulations, the resulting acoustophoretic flow had a peak enhancement at 110 Hz. Using these results, we printed nanoparticle suspensions under acoustic agitation and compared their surface fidelity with the intended CAD attributes, as well as compared to a simple pseudoplastic fluid (no nanoparticles, no yield stress). The overall effect is that our acoustophoretic polishing improves the printed feature resolution by over 25% compared to the normal inverted SLA process for yield stress fluids.