The production of new sources of protein with low environmental impact will guarantee the future of food security. Fungi are gaining importance as a promising source of food protein (mycoprotein) and also have the ability to produce surface-active proteins. This is the first time that the growing of Paradendryphiella salina (marine fungus) on Ulva spp. (green algae) through the submerged liquid fermentation for the production of mycoprotein (from mycelium) and hydrophobin like proteins (from culture broth) is reported. The nutritional composition of mycoprotein was investigated, obtaining a yield of 561.3 g of mycoprotein from 1 kg of dry algae, a good concentration of total protein (48.2 g/100 g), and a considerable concentration of total amino acids (21 g/ 100 g). The characterization of surface-active protein displays consistent behaviors with the class II hydrophobin. This study proves that sustainable production of mycoproteins and surface-active proteins can be developed growing a marine fungal strain, contributing to shed light on the potentiality of an integrated method that promotes the circular economy.