This study analyzed the quality characteristics of nutritional bars with varying concentrations (0, 0.5, 1.5, 2.5%) of Enteromorpha intenstinalis powder added. To achieve this, color analysis, an assessment of DPPH radical scavenging activities, and sensory evaluations were performed. The results revealed that as the amount of Enteromorpha intestinalis powder (EIP) increased, pH and lightness values decreased. DPPH radical scavenging activities of 75.26%, 56.11%, 71.59%, and 62.49% were exhibited for the 0%, 0.5%, 1.5%, and 2.5% concentrations, respectively at 50 mg/mL. Significant differences were observed between the samples with respect to the color, appearance, texture, taste, and overall preference for the nutritional bars. Overall preference was highest for the nutritional bar with 1.5% Enteromorpha intenstinalis powder added. Therefore, adding 1.5% of Enteromorpha intenstinalis powder to a nutritional bar is most suitable for enhancing preference and quality characteristics.