Abstract: In recent years, smart watches and folding-screen phones have become increasingly popular in the electronic market. This trend signifies that consumers nowadays not only pursue high performance of electronic devices but also demand higher comfort from electronic devices. With the improvement of material properties and progress in microelectronics technology, flexible materials and electronic devices have developed rapidly in recent years, forming a research hotspot in the electronics industry. Flexible electronic devices can achieve different deformation states owing to their small size, deformability, and portability. Unlike traditional electronic devices integrated with rigid materials such as silicon, flexible electronic devices can also undergo various mechanical deformations such as stretching, torsion, bending, and folding during usage, which meets the people's requirements for portable, lightweight, and deformable electronic devices. The unique characteristics of flexible electronic devices and materials will promote the innovative development of electronic skin, smart robots, artificial prostheses, implantable medical diagnosis, flexible displays, and the Internet of Things, which will eventually result in tremendous changes in our daily lives. As a new generation of metal materials, high-entropy alloys and metallic glasses have exhibited excellent physical, chemical, and mechanical properties owing to their unique structural characteristics, which show great potential in flexible electronics applications. However, the rigidity of the material itself cannot meet the requirements of deformable electronic devices. Therefore, it is necessary to realize the desired flexibility in these materials by reducing dimensions and designing microstructures. This paper briefly described the mechanical properties and preparation methods of high-entropy fibers and introduced the preparation methods, structural characteristics, and unique properties of high-entropy films as potential flexible materials. Applications of metallic glass in electronic skin, flexible electrodes, and microstructure designing were then summarized. Finally, the shortcomings of the existing work were discussed and the prospects for the development of flexible electronics in the future were presented.