Microwave absorbing materials (MAMs) are playing an increasingly essential role in the development of wireless communications, high-power electronic devices, and advanced target detection technology. MAMs with a broad-bandwidth response are particularly important in the area of communication security, radiation prevention, electronic reliability, and military stealth. Although considerable progress has been made in the design and preparation of MAMs with a broad-bandwidth response, a number of challenges still remain, and the structure–function relationship of MAMs is still far from being completely understood. Herein, the advances in the design and research of MAMs with a broad-bandwidth response are outlined. The main strategies for expanding the effective absorption bandwidth of MAMs are comprehensively summarized considering three perspectives: the chemical combination strategy, morphological control strategy, and macrostructure control strategy. Several important results as well as design principles and absorption mechanisms are highlighted. A coherent explanation detailing the influence of the chemical composition and structure of various materials on the microwave absorption properties of MAMs is provided. The main challenges, new opportunities, and future perspectives in this promising field are also presented.