Seaweed has rapidly transitioned from a mere coastal curiosity to a multifaceted resource across various industries, fueled by ecological awareness and technological breakthroughs. This versatile marine crop offers transformative potential in addressing global challenges related to food security, environmental conservation, sustainable agriculture, and resource management. Seaweeds contribute nutrient-dense food sources, function as bioindicators of pollution, and act as potent carbon sinks, significantly mitigating climate change impacts. The integration of cutting-edge genetic engineering techniques further amplifies seaweed’s utility by enhancing traits like accelerated growth rates, bolstered nutritional profiles, and improved resistance against environmental stressors and diseases. These technological interventions are pivotal for the sustainable expansion of large-scale seaweed cultivation systems. Moreover, seaweeds harbor a wealth of bioactive compounds such as polysaccharides, polyphenols, and essential amino acids, rendering them valuable candidates for functional foods, nutraceuticals, and pharmaceuticals. Precise genome editing tools like CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-Cas9 enable the development of biofortified seaweed varieties with enhanced nutrient bioavailability and desired amino acid compositions. Additionally, genetic engineering presents opportunities to modulate enzymatic pathways, optimizing seaweed’s antioxidant properties. The commercial applications of seaweed extend into realms like cosmetics and biofuel production, exemplifying its versatility and eco-friendly nature. By exploring the multidimensional benefits and prospects of seaweed, this chapter accentuates its indispensable role as a sustainable resource to address global demands for food, health products, and environmental remediation.