MYB transcription factors (TFs) participate in many biological processes. However, the molecular mechanisms by which MYB TFs affect plant resistance to apple ring rot remain poorly understood. Here, the R2R3-MYB gene MdMYB73was cloned from “Royal Gala” apples and functionally characterized as a positive regulator of the defense response to Botryosphaeria dothidea. qRT-PCR and GUS staining demonstrated that MdMYB73was strongly induced in apple fruits and transgenic calli after inoculation with B. dothidea. MdMYB73overexpression improved resistance to B. dothideain apple calli and fruits, while MdMYB73suppression weakened. Increased resistance to B. dothideawas also observed in MdMYB73-expressing Arabidopsis thaliana. Interestingly, salicylic acid (SA) contents and the expression levels of genes related with SA synthesis and signaling were greater in MdMYB73-overexpressing plant materials compared to wild-type controls after inoculation, suggesting that MdMYB73 might enhance resistance to B. dothideaviathe SA pathway. Finally, we discovered that MdMYB73 interacts with MdWRKY31, a positive regulator of B. dothidea. Together, MdWRKY31 and MdMYB73 enhanced B. dothidearesistance in apples. Our results clarify the mechanisms by which MdMYB73 improves resistance to B. dothideaand suggest that resistance may be affected by regulating the SA pathway.