To develop novel electromagnetic interference (EMI) shielding materials, polyaniline (PAni) composites filled with graphene, graphene decorated with silver nanoparticles (Ag@graphene), and graphene decorated with nickel nanoparticles (Ni@graphene) were prepared, and the microstructures, morphologies, electrical conductivities, and EMI shielding efficiencies (EMI SEs) of the composites with different filler loadings (0.5, 1.0, 3.0, and 5.0. wt.%) were investigated. The PAni composite containing 5.0. wt.% Ag@graphene showed the best electrical conductivity of 20.32. S/cm and highest EMI SE of 29.33. dB. The uniform dispersion of fillers significantly enhanced the formation of conductive pathways in the PAni matrix, and the presence of metal nanoparticles on the graphene surface and between the graphene layers also increased the electrical conductivity. The results of this study show that absorption is the primary factor governing EMI shielding, which is attributed to the high permittivity of the composites. This study reveals that the Ag@graphene/PAni composite is promising for applications as an EMI shielding material. © 2013 Elsevier Ltd.