The article provides an in-depth review of the pharmacological properties of the brown seaweed Undaria pinnatifida which is traditionally consumed in East Asia, this macroalga is recognized not only for its nutritional value but also for its potential in treating various health conditions. The current scientific evidence on the bioactive compounds found in U. pinnatifida, such as fucoxanthin, fucosterol, fucoidan, alginate, and dietary fiber have demonstrated significant pharmacological activities, including immunomodulation, antitumor, antiviral, antioxidant, antidiabetic, anti-inflammatory, anticoagulant, antithrombotic, and antibacterial effects, all with low toxicity and minimal side effects. It highlights the therapeutic potential of these bioactive constituents in the prevention and treatment of neurodegenerative and chronic diseases, emphasizing their mechanisms of action and therapeutic applications. This review underscores the potential role of Undaria pinnatifida as a source of natural bioactive compounds with diverse pharmacological benefits.