Originally, the term nori was generic and referred to seaweeds including hijiki. One of the oldest descriptions of nori is dated to around the 8th century. In the Taihō Code enacted in 701, nori was already included in the form of taxation. Local people have been described as drying nori in Hitachi Province Fudoki (721–721), and nori was harvested in Izumo Province Fudoki (713–733), showing that nori was used as food from ancient times. In Utsubo Monogatari, written around 987, nori was recognized as a common food. The original nori was formed as a paste, and the sheet form was invented in Asakusa, Edo (contemporary Tokyo), in the Edo period through the method of Japanese paper-making.
The word "nori" first appeared in an English-language publication in C. P. Thunberg's Trav., published in 1796. It was used in conjugation as "Awa nori", probably referring to what is now called aonori.
The Japanese nori industry was in decline after WWII, when Japan was in need of all food which could be produced. The decline was due to a lack of understanding of the plant's three stage life cycle so that local people did not understand why traditional cultivation methods were not effective. The industry was rescued by knowledge deriving from the work of British phycologist, Kathleen Mary Drew-Baker who had been researching the organism porphyria umbilicalis, which grew in the seas around Wales and was harvested for food, as in Japan. Her work was discovered by Japanese scientists who applied it to artificial methods of seeding and growing the plants, rescuing the industry. Kathleen Baker was hailed as the 'Mother of the Sea' in Japan and a statue erected in her memory.