 Ternary-layered materials are a relatively new class of two-dimensional, 2D materials that can be produced by combining three different layers of elements or compounds. These materials offer a wide range of potential applications due to their unique structure and properties. This review focuses on the synthesis and exploration of these materials, discussing their compositions, structures, and properties. It also highlights the differences between the materials based on their stoichiometry and interlayer interactions, and how these differences affect the resulting 2D materials. Finally, it examines the potential applications of these materials in electronics, optoelectronics, and energy storage and conversion. This article was authored by Jing Peng, Zheng Jieqian, Bao Fuding, and others.