Potassium-ion batteries (KIBs) are one of the most promising large-scale electric energy storage systems due to the high abundance and low redox potential of K. As the key component, anode determines their energy density and safety. Alloy-based anodes, such as P, Sn, Sb, and Bi, have attracted extensive attention due to their abundant resources, suitable working potentials, and large theoretical capacities. However, the dramatic volume variation upon (de)potassiation results in pulverization of particles and their detaching from the current collector accompanied with performance decay. Various strategies, including designing micro-/nanostructures, introducing carbon substrates, and optimizing electrode/electrolyte interface, have been demonstrated to effectively alleviate these issues. Herein, we summarize the recent research progresses on alloy-based materials in KIBs. The synthesis methods, electrochemical performance, reaction mechanisms, and structure–activity relationships of these materials are considered, and challenges and perspectives are provided. This review provides new insight into designing of high-activity electrode materials for KIBs and beyond. Graphic abstract