To identify genomic loci with an effect on meat quality traits in Hanwoo cattle, 3,000 animals with carcass phenotypes were genotyped with a customized 56K Affymetrix SNP chip. Genome-wide association studies (GWAS) were performed for marbling (MAR), maturity (MAT), back-fat thickness (BFT), loin eye area (LEA), carcass weight (CAW), meat quality grade (MQG), and meat yield grade (MYG). Multiple statistically significant SNP were identified for MAT (674 SNP), MAR (595), CAW (754), LEA (506), BFT (440), MYG (496), and MQG (2,850) with chromosomes 14 and 23 having extreme significant associations for CAW and MYG, respectively. A 66-bp insertion in ADIPOQ from 81966364 to 81966419 was genotyped by agarose gel electrophoresis in 3,000 animals to verify the associations of GWAS loci located in the ADIPOQ region. The ADIPOQ insertion was significantly associated with MAR (P = 0.034), BFT (P = 0.004), LEA (P = 0.014), CAW (P = 0.002), and MYG (P = 0.003). This study’s significant SNP may be used in marker-assisted selection programs to improve meat quality traits in beef cattle.