Highly flexible electromagnetic interference (EMI) shielding material with excellent shielding performance is of great significance to practical applications in next-generation flexible devices. However, most EMI materials suffer from insufficient flexibility and complicated preparation methods. In this study, we propose a new scheme to fabricate a magnetic Ni particle/Ag matrix composite ultrathin film on a paper surface. For a ~ 2-µm-thick film on paper, the EMI shielding effectiveness (SE) was found to be 46.2 dB at 8.1 GHz after bending 200,000 times over a radius of ~ 2 mm. The sheet resistance (R□) remained lower than 2.30 Ω after bending 200,000 times. Contrary to the change in R□, the EMI SE of the film generally increased as the weight ratio of Ag–Ni increased, in accordance with the principle that EMI SE is positively related to an increase in electrical conductivity. Desirable EMI shielding ability, ultrahigh flexibility, and simple processing provide this material with excellent application prospects.