Seaweeds or marine algae are rich in minerals and nutrients that are important for most of the biochemical reactions and non-nutrient components like dietary fibres and polyphenols. The present study aims at elucidating the nutritional composition of the two marine algae Gelidiella acerosa (red seaweed) and Sargassum wightii (brown seaweed) and the results revealed that the seaweeds possess high fibre content of 13.45±1.076% and 17±1.19% DW and ash content of 0.103±0.049g/g DW and 0.25±0.02g/g DW respectively. Nutritional composition analysis showed that the carbohydrate, protein, lipid, proline and chlorophyll contents of the seaweeds were high. Evaluation of mineral content demonstrates that the concentration of potassium was high in G. acerosa, whereas S. wightii was found to possess high amount of Sodium. Fatty acid profile verified the presence of major fatty acids with high nutritional value including, linolenic acid and α-linolenic acid. Amino acid composition showed that both the seaweeds possess most of the essential amino acids including valine, methionine, lysine and phenyl alanine. Vitamin analysis revealed the presence of high amount of vitamin C (an antioxidant) in the seaweeds. The results suggest that both the seaweeds have greater nutritional value and could be used as excellent nutritional supplements.