In barley, semi-dwarf varieties are attractive for their superior harvest index and lodging resistance, but many semi-dwarf barley genotypes suffer from poor spike emergence. We performed a genetic characterization of a semi-dwarf line (ND23049) that combines short stature, strong stiff culms, and adequate spike emergence. We developed a doubled haploid (DH) population derived by crossing ND23049 and the cultivar CLE253. A subset of 88 DH lines and parents were characterized for plant height in 2013 and 2014 and genotyped. In total, 1984 SNPs (345 unique loci) were used to produce a linkage map of 1127.1 cM. Three QTLs for plant height were detected in this population and coincided with the HvGA20ox2/Sdw1, HvBRI1/Uzu1, and HvPRR95 gene loci. The phenotypic variation explained by each QTL was 75.8%, 7.7%, and 4.1%, respectively, and jointly explained 83.3% (2013) and 87.7% (2014) of plant height. Our results suggest that ND23049 contributed the “short” allele at the HvGA20ox2/sdw1 locus while CLE253 provided “short” alleles at the HvBRI1/uzu1 and HvPRR95 loci. We identified a large deletion (at least 92.7 Kb), including HvGA20ox2 (Sdw1), as the causal mutation in ND23049. A set of tightly flanked SNP markers will help breeders to develop improved semi-dwarf varieties.