The stored carbon in the thallus of three seaweed species (Enteromorpha intestinalis, Ulva lactuca and Catenella repens) was estimated in three different seasons (pre-monsoon, monsoon and post-monsoon) from four sampling localities in the deltaic ecosystem of Indian Sundarbans (21040/ N to 22040/N and 88003/E to 89007/E). The average stored carbon content varied from 1022.18 g m-2 (during monsoon) to 1067.02 g m-2 (during pre-monsoon) in Enteromorpha intestinalis. In Ulva lactuca, the stored carbon ranged from 46.41 g m-2 (during post-monsoon) to 152.43 g m-2 (during pre-monsoon). In case of Catenella repens, the range of stored carbon is 13.70 g m-2 (during monsoon) to 51.44 g m-2 (during pre-monsoon). Amongst the seaweed species undertaken in the study, E. intestinalis showed uniformity in biomass between sectors (pcal = 1.62 < pcrit = 18.51) and seasons (pcal = 2.43 < pcrit = 4.14), which implies tolerance of the species to variable salinity. Highest values of stored carbon were recorded in E. intestinalis, which might indicate its role as potential candidate species in the blue carbon series of Indian Sundarbans deltaic complex.