The objective was to determine the effects of degree of steam flaking of corn (SFC) on performance of finishing cattle fed diets containing wet distillers grains with solubles (WDGS). Crossbred steers (n = 214: initial BW = 357 ± 26.0 kg) and heifers (n = 121: initial BW = 323 ± 30.9 kg) were randomly assigned to 54 pens and 6 diets containing 0, 15, or 30% WDGS and corn steam flaked to either 321 or 270 g/L bulk density (25 or 21 lb/bu, respectively) in a 2 × 3 factorial arrangement. There were no interactions between WDGS concentration and SFC bulk density for growth performance ( P > 0.48), and growth performance was not influenced by the degree of steam flaking of corn ( P > 0.29). Dry matter intake ( P < 0.15) and ADG ( P < 0.06) tended to respond quadratically to dietary WDGS. Gain efficiency tended ( P = 0.15) to decrease linearly as dietary WDGS concentration increased. Carcass characteristics were not affected by SFC density but hot carcass weight ( P < 0.12), DP ( P < 0.01), and YG ( P < 0.14) were affected by WDGS concentration. Decreasing bulk density of SFC tended ( P < 0.11) to increase the frequency of liver abscesses. Results suggest optimal performance is achieved in SFC-based finishing diets when WDGS is fed at 15% of DM and that increasing the degree of steam flaking of corn to less than 321 g/L does not improve cattle performance in diets containing WDGS.