This review summarizes recent advances in multifunctional metamaterials (MF-MMs) for electromagnetic (EM) wave absorption. MF-MMs overcome the key limitations of conventional absorbers—such as narrow bandwidth, limited functionality, and poor environmental adaptability—offering enhanced protection against EM security threats in radar, aerospace, and defense applications. This review focuses on an integrated structure-material-function co-design strategy, highlighting advances in three-dimensional (3D) lattice architectures, composite laminates, conformal geometries, bio-inspired topologies, and metasurfaces. When synergized with multicomponent composites, these structural innovations enable the co-regulation of impedance matching and EM loss mechanisms (dielectric, magnetic, and resistive dissipation), thereby achieving broadband absorption and enhanced multifunctionality. Key findings demonstrate that 3D lattice structures enhance mechanical load-bearing capacity by up to 935% while enabling low-frequency broadband absorption. Composite laminates achieve breakthroughs in ultra-broadband coverage (1.26–40 GHz), subwavelength thickness (<5 mm), and high flexural strength (>23 MPa). Bio-inspired topologies provide wide-incident-angle absorption with bandwidths up to 31.64 GHz. Metasurfaces facilitate multiphysics functional integration. Despite the significant potential of MF-MMs in resolving broadband stealth and multifunctional synergy challenges via EM wave absorption, their practical application is constrained by several limitations: limited dynamic tunability, incomplete multiphysics coupling mechanisms, insufficient adaptability to extreme environments, and difficulties in scalable manufacturing and reliability assurance. Future research should prioritize intelligent dynamic response, deeper integration of multiphysics functionalities, and performance optimization under extreme conditions.