Peanut (Arachis hypogaea L.), as an important oilseed and economic crop in China, is susceptible to various pathogens during its growth, development, and storage, posing a serious threat to its yield and quality. With the completion of whole-genome sequencing of peanut, the mapping of disease resistance quantitative trait loci (QTL) and molecular-assisted breeding technologies have achieved rapid development, providing a new and effective technical support for the genetic improvement of peanut. This review systematically summarized the construction of peanut genetic maps and the mapping of QTLs associated with major peanut diseases, including leaf spot, bacterial wilt, stem rot, and Aspergillus flavus. To drive the genetic improvement of disease resistance in peanuts, a synergistic strategy combining multi-omics analyses, molecular marker-assisted selection, and precision gene editing technologies must be implemented to enable transformative advances in peanut breeding.