Pre-harvest sprouting (PHS) poses a major threat to wheat yield and quality, yet the genetic basis of seed dormancy underlying PHS resistance remains poorly understood. Here, through integrated genome-wide association and transcriptomic analyses, we identify TaMYB7-A1 as a key regulator of seed dormancy and PHS resistance. TaMYB7-A1 encodes an R2R3-MYB transcription factor that directly activates TaABI5 to modulate abscisic acid (ABA) signaling and indirectly fine-tunes ABA-gibberellin (GA) homeostasis to enforce dormancy. Evolutionary and haplotype analyses revealed that the superior allele, TaMYB7-A1Hap-1, originated from wild einkorn and was introgressed into domesticated emmer and subsequently into modern bread wheat. A miniature inverted-repeat transposable element (MITE) insertion in its promoter substantially elevates TaMYB7-A1 expression by increasing chromatin accessibility and facilitating the recruitment of upstream regulators, while two key amino acid substitutions (Gly23 and Gly92) strengthen its DNA-binding and transcriptional activation capacity. Combinations of promoter and coding-region variants generate graded PHS resistance across haplotypes, mirroring local adaptation to harvest-season precipitation. Introgression of TaMYB7-A1Hap-1 into modern cultivar enhances PHS resistance without yield penalties. These findings elucidate a molecular and evolutionary framework for precipitation-driven adaptation and provide a valuable genetic target for developing climate-resilient wheat varieties.