Seaweeds have been foundational in the subsistence, culture, and economies of Indigenous coastal communities across temperate regions for millennia. In Southeast Alaska, Indigenous groups such as the Tlingit, Haida, and Tsimshian developed intricate traditional knowledge systems governing the sustainable harvest, use, and stewardship of various seaweed species, e.g., Pyropia abbottiae, Devaleraea mollis, and Nereocystis luetkeana. With the rise of seaweed aquaculture in Alaska and the broader global demand for seaweed-derived products, there is growing recognition of the value of integrating traditional ecological knowledge (TEK) into developing a resilient “phyconomy.” This chapter explores historical and contemporary seaweed practices in Alaska, highlighting how TEK aligns with modern sustainability frameworks such as the Blue Economy. It also evaluates the ecological and economic implications of expanding aquaculture while preserving cultural heritage. Challenges remain, including fragmented policy, limited processing infrastructure, and environmental stressors affecting wild populations. Nonetheless, Alaska’s efforts, such as Indigenous-led initiatives, sustainable harvest protocols, and state support for seaweed farming, illustrate a promising model for temperate regions worldwide seeking to balance ecological, cultural, and economic objectives through inclusive and sustainable seaweed industry development.