Plant-based lectins are promising biotechnological sources that also gain prominence when applied to pharmacology, especially seaweed lectins. Lectins exhibit various biological activities such as antioxidant, antifungal, antibacterial, and anticancer. Chaetomorpha aerea contains lots of bioactive compounds, notably lectin. Viscozyme L enzyme and microwave were used to improve the efficiency of lectin extraction from C. aerea alga. This study investigated the effects of Viscozyme L and microwave treatment on lectin extraction from C. aerea. The results showed that the enzyme-assisted extraction (EAE) method resulted in a protein content of 0.098 g/g DM, and hemagglutinating activity (HA) of 3,521.075 HU/g. During microwave-assisted extraction (MAE), the obtained protein content was 0.101 g/g DM and the HA was 4,377.739 HU/g