Grain protein content (GPC) is a quantitative trait that strongly influences wheat processing quality and end-product performance, but is highly affected by environmental conditions. This study aimed to identify QTLs associated with GPC using Korean wheat resources and assess the usefulness of linked markers for selection. A recombinant inbred line (RIL) population (F₇ and F₈; n=359) derived from ‘Joongmo2008’ × ‘Joah’ was genotyped with a 35 K SNP array, and QTL mapping was conducted using 4,891 filtered SNPs. Six QTLs were detected, and a major QTL on chromosome 3 B (Qgpc-3B) was consistently identified in both generations. Within the Qgpc-3B interval, lines carrying the ‘Joongmo2008’ alleles at AX-95163812 and AX-94495360 showed higher GPC, and the same trend was confirmed by a two-marker haplotype analysis. The direction of marker effects was also reproduced in a Korean wheat germplasm panel, suggesting that these markers have strong potential as practical selection indices for improving GPC in wheat breeding programs.