Abstract: Developing lightweight and flexible thin films for electromagnetic interference (EMI) shielding is of great importance. Porous thin films of reduced graphene oxide containing SiC whiskers (SiC@RGO) for EMI shielding were prepared by a two-step reduction of graphene oxide (GO), in which the two steps were chemical reduction by HI and the solid phase microwave irradiation. A significant increase of the film thickness from around 20 to 200 μm was achieved due to the formation of a porous structure by gases released during the 3 s of solid phase microwave irradiation. The total shielding effectiveness (SE_T) and the reflective SE (SE_R) of the SiC@RGO porous thin films depended on the GO/SiC mass ratio. The highest SE_T achieved was 35.6 dB while the SE_R was only 2.8 dB, when the GO/SiC mass ratio was 4∶1. The addition of SiC whiskers was critical for the multi-reflection, interfacial polarization and dielectric attenuation of EM waves. A multilayer film with a gradient change of SE values was constructed using SiC@RGO porous films and multi-walled carbon nanotubes buckypapers. The highest SE_T of the multilayer films reached 75.1 dB with a SE_R of 2.7 dB for a film thickness of about 1.5 mm. These porous SiC@RGO thin films should find use in multilayer or sandwich structures for EMI absorption in packaging or lining.