Dorper sheep (DOR) are a commercially important mutton breed renowned for their high growth rate, favorable carcass composition, environmental adaptability, and natural wool shedding. In China, they are widely utilized as terminal sires to enhance growth and carcass yield in local breeds. To elucidate the genetic basis of these traits, we sequenced the genomes of 20 DOR and integrated the data with whole-genome sequences from 73 individuals representing four Chinese indigenous breeds. Analyses of genetic diversity, inbreeding coefficients, and population structure revealed reduced genomic diversity, elevated inbreeding levels, and clear genetic separation for DOR from other indigenous breeds. Selective sweep scans using F_ST, pi, and XP-EHH identified candidate genes involved in five major trait categories: growth performance and development (COL2A1, DAB2IP, EPYC, TSPAN18, WNT1, CTPS1, FBXW7, INSR, S100A6, SOCS2), energy metabolism (ACSS3, ADGRE3, CPT2, GCGR, PRKAA1), fat deposition and adipocyte differentiation (EHBP1, FOXP1, KLF12, PDGFD, RALGAPA2), immune response (CXCR6, IL17RB, NFKBIZ, TMEM154), and wool traits (CERS4, MITF). These results will provide novel insights into the genomic architecture of economically important traits in DOR and support their genetic improvement through informed crossbreeding with Chinese local breeds.