In this work muscovite was ultrasonically treated to obtain composites with post-industrial wood plastic residues. The muscovite was ultrasonicated for 30 or 60 min and mixed with the polymeric matrix at a constant level of 15% (weight percentage). The composites were prepared in a single-screw extruder and formed into flat films for characterization. SEM images of the ultrasonicated muscovite revealed the occurrence of delamination, while the particle size distribution results suggested a decrease in size with longer sonication time. FTIR spectra also indicated the occurrence of delamination of the material. The composites exhibited a slight increase in density and a large increase in impact resistance of the samples with ultrasonicated muscovite. The XRD of the composites suggested the occurrence of alignment of the mineral in the matrix. The results indicate that ultrasonication is an effective method to improve the interaction and dispersion of muscovite with wood plastic waste to obtain composites.