As Asia is the world’s leading producer of seaweed, India will have the opportunity to take advantage of its plentiful coastal shorelines and become one of the leaders in seaweed farming. Seaweeds play a major role in providing food, fodder, medicine, cosmetics, energy, and fertilizer, and people use them in the industrial production of agar and alginate (hydrocolloids). On average, seaweeds grow faster than land plants, thereby making them an attractive choice for providing food and raw materials for various products. However, seaweed farming, which is being practiced today, needs to grow at a bigger scale to meet the global requirements of consumers in this particular domain. Seaweed-derived biostimulants (SDS) accelerate growth along with biomass yield and assist significantly in improving agronomic production, crop health, and quality. It has been found in many research studies that seaweed extracts of different seaweed origin significantly affect crop productivity, but their use in seaweed farming is minimal. This chapter discusses the biostimulant property of seaweed extract, its effect on seaweed physiology, biochemical traits, mode of action, and its application for large-scale seaweed farming. It is also unknown why seaweed extract affects other seaweeds’ physiology and disease-resistance capabilities. This chapter discusses the use of SDS in field and laboratory conditions for improved seaweed productivity, disease tolerance, resistance against epiphytes, byproduct yield, survival, and regeneration.