Veganism has recently become more popular for ethical, health, and environmental reasons. Despite its benefits, many vegans struggle to obtain a complete essential amino acid profile from plant sources alone. Diversification of protein sources is crucial for a balanced amino acid intake and adequate nutrition. Macroalgae, a nutrient-rich food that has long been consumed in Asia, offers one solution. Essential and non-essential amino acids, vital for optimal health, are found in edible macroalgae species. In this study, the amino acid profiles of seven macroalgae species, four brown algae species, namely Pelvetia canaliculata, Saccharina latissima, Fucus vesiculosus and Laminaria ochroleuca, and three red algae species, namely Gigartina pistolita, Mastocarpus stellatus, Chondrus crispus from the northwest coast of the Iberian Peninsula, were analyzed using HPLC with fluorescence detection. Essential amino acids were found in all algae samples, except for tryptophan, which was absent in all but Fucus vesiculosus. The amino acids detected in greater quantity in the Phaeophyceae species were aspartic and glutamic acids. These amino acids are responsible for the “unami” flavor. In the Rhodophyta group, aspartic and glutamic acids are also present in large quantities, but higher concentrations of histidine and lysine were found. The findings of this study are of utmost importance, revealing that macroalgae are a valuable food source that provides a comprehensive profile of essential amino acids. This is particularly crucial for personalized nutrition plans for vegetarian and vegan diets, shedding new light on the potential of macroalgae in the field of nutrition.