Algae represent a large and new source of nutrients with other health benefits as supplements in animal feed formulations. ‘Algae’ is a generic term that groups brown, green, and red types of both macro- and micro-algae. These marine plants may play a key role in the future for poultry production, as they constitute a new and valuable nutrient source, thanks to their nutritional composition and richness in as polyphenols, polysaccharides and fatty and amino acids. Many studies have evaluated the advantages and inconvenience of using micro- and macro-algae in poultry nutrition and their ability to improve animal health and, thus, welfare. This review describes the main nutritional characteristics of algae and the current knowledge on their effects in poultry production, impacts on animal health, growth performance and product quality (eggs and meat). The increase in laying rate and egg weight can reach +4.0 to 8.6 percentage points and +1.3 to 1.5 g, respectively. The increase in body weight of broilers and decrease in feed conversion ratio can vary from 5% to 22% and from 4% to 15%, respectively. According to the literature, a dietary incorporation rate of 2% for microalgae or a range between 1% and 5% for macroalgae is suitable for both laying hens and broiler chickens, even though these ranges greatly depend on the type of algae used and the expected benefits for poultry production.