This study was conducted to investigate the effect of feeding whole crop barley silage (WBS) on the growth performance, carcass grade, and beef quality of Hanwoo steers. Twelve Hanwoo steers (12-mon-old) were allocated into either a control (rice straw fed) or WBS (whole crop barley silage fed) group (six animals per group) and fed for 540 d until the animals reached 30-mon-old. Concentrates and roughage were fed according to the feeding stage phases; finisher I (12-16-monold), II (17-21-mon-old), and III (22-30-mon-old). A significant increase in growth was observed during the finisher I stage for the steer fed WBS, whereas a significant increase in growth occurred during the finisher II stage in the control group. The yield grade of the WBS group increased significantly with a 15.6% increase in the longissimus dorsi area and a 25.7% reduction in back fat thickness. Marbling scores improved 52.4% in the WBS group compared with the control group. A significant difference in treatments was observed for the proximate chemical composition of the crude fat content. The results regarding palatability traits in the WBS group showed a significant improvement in appearance. The results indicate that the WBS group had improved longissimus muscle and marbling scores on carcass grading compared to the control.