Potassium-ion batteries (PIBs) are highly attractive and are promising energy storage technology because of their cost-effectiveness, superior safety, environmental friendliness, as well as high standard K/K⁺ redox potential, and abundance and low cost of potassium. Transition metal disulfides (TMDs) have a wide interlayer spacing that is attractive as a K⁺ storage site in PIBs. Moreover, TMDs have high reversible capacity and are low cost. Nevertheless, they have not been extensively studied. The practical application of TMDs is impeded by their fast capacity fading and poor rate performance. More well-focused research should aim for the commercialization of TMDs in PIBs. This paper reviews (a) the main strategies to enhance the application of TMDs in PIBs; (b) the recent development of using TMDs such as MoS₂, WS₂, and SnS₂ as electrode materials for PIBs, including their structure, performance, and defects, as well as the methods to alleviate their defects; (c) the associated electrochemical processes; and (d) the critical issues, challenges, and prospects.