Abstract: This review summarizes the latest research progress in foamed polymer composites for electromagnetic wave absorption, with a systematic focus on the fundamental principles of electromagnetic wave absorption and the wave-absorbing performance of composite foams incorporating different types of fillers. In the domain of carbon-based/polymer foams, a detailed introduction is provided for composite foaming systems combining polymers with carbon fibers (CF), carbon nanotubes (CNTs), and graphene nanoplatelets (GnP). These carbon-based fillers effectively enhance the electromagnetic wave loss capability of the composites owing to their excellent high conductivity, low density, and favorable interfacial compatibility. In the field of ceramic/polymer foams, the wave-absorbing performance of ceramic fillers such as silicon carbide (SiC) and ferrous-ferric oxide (Fe₃O₄) within foamed polymer matrices is outlined. These composites can maintain stable wave-absorbing efficiency even under harsh service conditions, including high temperatures and corrosive environments. By tailoring the pore structure of the composites, this work aims to leverage foaming technology for lightweight material design while utilizing the resulting porous interfaces to optimize electromagnetic impedance matching and promote multiple scattering, thereby synergistically improving the overall wave-absorbing performance. This research strategy provides novel insights and technical references for developing next-generation lightweight, broadband, and high-efficiency electromagnetic wave-absorbing materials. However, key bottlenecks remain in current research. Achieving precise control over the three-dimensional pore structure to realize optimal synergy between impedance matching and loss mechanisms, as well as balancing structural stability and mechanical properties while preserving the material's low-density advantage, represent core research directions requiring focused exploration in the future.