This study aimed to develop a novel functional jelly by incorporating dieckol-rich extracts from (). In the extraction process, a high dieckol yield (16.5 mg/g biomass) was achieved by response surface optimization (optimum conditions: 55.3 % prethanol A, 70.9 °C, and 87.3 min). Dieckol jellies (DJs) were produced by adding various amounts of the extract with 25, 50, 75, and 100 % of 9.954 mg (recommended daily intake). The antioxidant activity of DJ increased from 0.02 to 0.4 mg ascorbic acid equivalent/mL with increasing dieckol content, and the texture analysis showed increased hardness, adhesiveness, and chewiness in DJs with over 75 % dieckol. The sensory testing indicated that DJ 25 had a superior overall preference, comparable to DJ 0 and higher than DJ 50 - 100. This study confirmed that is a high-potential source of dieckol, and the developed DJ is expected to have high potential as a novel functional food.