The lion’s mane jellyfish Cyanea capillata consists of proteinaceous compounds with various biological activities such as haemolytic, cytotoxic, neurotoxic, cardiovascular and enzymatic properties. In the present study, crude and DEAE cellulose column fractionated toxin were prepared from the whole body extracts of Cyanea capillata. The toxins were evaluated for protein concentration and were investigated for haemolytic activity and Artemia toxicity. The most active fraction in both the assays was subjected to HPLC analysis to elucidate the bioactive proteins. The crude toxin had 230.15 μg.mL−1 protein. Whereas, the protein concentration ranged between 40.85 and 105.62 μg.mL−1 in the fractionated toxins. The crude as well as the fractionated toxins exhibited remarkable activity in both the assays with maximum activity in fraction 5. The HPLC analysis of the most active haemolytic fraction reveals a single prominent peak with a retention time of 1.79 min. Further study on the eluted peak would enable us to understand qualitative details of protein responsible for the haemolytic activity.