The invention relates to a method for obtaining antioxidant extracts from macroalgae using ultrasound-assisted continuous aqueous extraction. The process can be performed using fresh alga or dry alga, after resuspending same in water. A suspension of alga in water is prepared with a solid concentration of between 10 and 30%. The mixture is fed to an ultrasonic disruption system. The extract is filtered and lyophilized, obtaining total polyphenol concentrations of 62.4 mg eq. of phloroglucinol/g of lyophilisate with Bifurcaria bifurcata and 44 mg eq. of phloroglucinol/g of lyophilisate with Ascophyllum nodosum. The extract can be used as an ingredient in cosmetic and food formulations.
