In this study, we evaluated marbling fineness (MF) in Hanwoo steers using the F7 index derived from image analysis and estimated genetic parameters along with four carcass traits: carcass weight (CWT), back fat thickness (BFT), eye muscle area (EMA), and marbling score (MS). Phenotypic and genomic data from 1,156 animals were analyzed using the multi-trait genomic best linear unbiased prediction (GBLUP) model. The heritability of MF was estimated at 0.441, indicating moderate-to-high genetic control. MF exhibited a strong genetic correlation (r = 0.639) with MS, suggesting shared genetic influences between these marbling-related traits.The correlation between MF phenotypes and genomic estimated breeding values (gEBVs) was significant (r = 0.769, p < 0.001), and the mean prediction accuracy based on prediction error variance (PEV) was 0.714&#8212;comparable to the accuracies of the four carcass traits. To further improve the genetic gain of MF, expansion of the national reference population, refinement of environmental modeling, and development of more precise genomic prediction methods are recommended. These results highlight the MF’s potential as a novel economic trait in Hanwoo cattle and its value as a selection criterion for future genomic breeding programs aimed at enhancing beef quality.