In vitro antioxidant potential and metal chelating activity of various solvent fractions of Gelidiella acerosa were evaluated by different antioxidant assays, like ferric reducing antioxidative power (FRAP) assay and scavenging activities for hydrogen peroxide, hydroxyl radical and nitric oxide. Among all the fractions, benzene showed the highest 1,1-diphenyl,2-picrylhydrazyl (DPPH) radical, nitric oxide and hydrogen peroxide scavenging activity when compared to standard BHT with IC₅₀ values of 306.50±3.04, 328.79±14.25 and 275.43±72.99μg/mL, respectively. Total antioxidative capacity and reducing power was found to be significantly higher in the dichloromethane fraction. Highest ferrous ion chelating activity was observed in ethyl acetate and benzene fractions. Dimethylsulfoxide fraction exerted the highest hydroxyl radical scavenging effect. Moreover, benzene and dichloromethane fraction showed the highest total polyphenolic content of 18.86±0.27 and 17.69±0.353μg/mg of dry extract, respectively. Preliminary cytotoxic studies suggest that benzene and dichloromethane fraction has no cytotoxic effect, hence, they can be used as effective antioxidant for treating reactive oxygen species (ROS) mediated diseases.