This study investigated the physicochemical properties and antioxidant activities of yanggaeng prepared from agar, sugar, honey, oligosaccharide, cooked white bean paste, and different amounts (0, 0.5, 1.0, 1.5, 2.0, and 2.5%) of Pyropia yezoensis powder. The moisture, pH, sugar content, color, texture, antioxidant activity, and sensory properties of yanggaeng were investigated. The moisture content of yanggaeng did not change despite the increasing amount of P. yezoensis. The pH and sugar content decreased with increasing P. yezoensis concentration. The lightness decreased significantly, whereas the redness and yellowness increased with increasing amounts of P. yezoensis. Regarding texture profile analysis, the hardness, gumminess, chewiness, and cohesiveness decreased with increasing P. yezoensis content. The antioxidant activity of yanggaeng increased with increasing concentrations of P. yezoensis powder. Yanggaeng containing 2.5% P. yezoensis had the highest overall sensory acceptance score. Therefore, the addition of P. yezoensis to yanggaeng appears to improve its quality and antioxidant activity.