This study was conducted to investigate the effect of the addition of Hizikia fusiforme, Capsosiphon fulvescens, and Undaria pinnatifida sporophyll on the antioxidant and inhibitory potentials against key enzymes related to type 2 diabetes of a commercial vegetable extract. The nutritional quality and mineral concentration of a vegetable extract with seaweeds added were also analyzed. The addition levels of seaweed did not influence the proximate composition, whereas the calcium, sodium, potassium, magnesium, and iron concentrations significantly increased at the 5% Hizikia fusiforme and Undaria pinnatifida sporophyll addition levels. The 20% Hizikia fusiforme addition level significantly increased the total phenolic content and reducing power by 47.08% and 16.82%. The hydroxyl radical scavenging ability of the vegetable extract was not strengthened with the addition of seaweeds. The DPPH radical scavenging activity at the 20% Hizikia fusiforme, Capsosiphon fulvescens, and Undaria pinnatifida sporophyll addition levels significantly increased by 27.47%, 22.25%, and 17.27%, respectively. The vegetable extract with seaweeds added showed higher-level ${alpha}$-glucosidase inhibition activities, accompanied by relatively weaker ${alpha}$-amylase inhibition activity. In particular, at the 5% Undaria pinnatifida sporophyll addition level, the ${alpha}$-glucosidase activity was significantly inhibited by 98.26%. Overall, the results showed that the incorporation of seaweeds into a vegetable extract effectively increased the mineral concentration and improved the antioxidant and inhibitory abilities of the extract on key enzymes linked to type 2 diabetes.