<p>The aquaculture industry is a rapidly growing sector and a vital source of nutrients, with a projected 10% increase in production by 2032. This rapid growth has prompted the need to identify sustainable feed supplements, as many aquatic species require nutritionally balanced diets. To address this, brown algae have emerged as a promising feed supplement due to their rich content of carbohydrates, fatty acids, minerals, antioxidants, and other bioactive compounds, which can improve the health and performance of farmed species. This review describes brown algae, their main bioactive compounds, as well as their use as a supplement in aquaculture feeds using different inclusion percentages and the impact on zootechnical (growth rate, weight, and mortality) and physiological (digestive activity, immune response, among others) parameters in aquatic organisms. In addition, various processing techniques are discussed, including hydrothermal, enzymatic, supercritical fluid, ultrasonic, and fermentation methods, to improve bioavailability and reduce antinutritional factors. The challenges, future prospects, and economic implications of integrating brown algae into aquaculture feeds are also highlighted.</p> Graphical Abstract <p></p>