Freeze-dried Ecklonia cava powder was incorporated into cookie dough at 5 levels (0%, 1.5%, 3%, 4.5%, and 6%, w/w) by replacing equivalent amount of wheat flour of the cookie dough. After aging and sheeting, cookies were baked at 185oC for 14 min in a convection oven. The baked cookies were cooled to room temperature for 30 min and packed in airtight bags prior to all measurements. Lightness (L*) decreased significantly as the E. cava powder content increased (p<0.05) and a decreasing trend in both redness (a*-value) and yellowness (b*-value) was observed. On the other hand, firmness increased significantly with an increase in E. cava powder content (p<0.05). Increases in E. cava powder concentration up to 6% in the cookie formulation significantly increased the intensities of all sensory attributes such as color, flavor, taste, and firmness (p<0.05). Correlation analysis indicated that the E. cava concentration correlated significantly with most of the properties except for a*-value (p<0.01, 0.05, or 0.001). Properties such as firmness and sensory color and firmness correlated positively while L*- and b*-values correlated negatively with E. cava concentration. Sensory color correlated negatively with L*- and b*-values. Sensory firmness correlated positively with mechanically measured firmness.