Electromagnetic interference has become a serious pollution concern in modern society, which has significantly driven the development of lightweight electromagnetic interference shielding materials based on porous carbon/polymer nanocomposites. This work discusses the state-of-the-art methods for fabricating polymer foams and carbon foams, aerogels, and sponges for electromagnetic interference shielding. In order to obtain an ideal electromagnetic interference shielding effectiveness, it is crucial to create carbon/polymer nanocomposites with effective conductive networks at low filler loadings. To this end, there have been three design strategies, including the use of carbon foams with polymer backfilling, the use of carbon-based hybrid fillers, and the formation of segregated structures in conductive polymer composite. This review also discusses electrical conductivity and electromagnetic interference shielding performances as well as associated mechanisms behind of lightweight carbon-polymer nanocomposites, and their potential applications are summarized. Some key challenges on lightweight polymer-carbon nanocomposites as electromagnetic interference shielding materials are presented followed by some future perspectives.