We propose a new way to create tunable superlattices by launching two surface acoustic waves on a piezoelectric substrate that hosts a two-dimensional quantum material. This “acoustoelectric superlattice” offers two unique advantages: its periodicity can be widely adjusted, bridging the gap between moiré and optical lattices, and its strength can be directly tuned by the acoustic wave power. Using massive monolayer graphene as an example, we demonstrate that varying the frequencies and power of the surface acoustic waves enables in-situ control over the band structure of the 2D material, generating flat bands and tunable nontrivial valley Chern numbers, featuring a highly localized Berry curvature.