Kaumualiʻi (c. 1778–May 26, 1824) was the last independent aliʻi nui (supreme ruler of the island) of Kauaʻi and Niʻihau before becoming a vassal of Kamehameha I within the unified Kingdom of Hawaiʻi in 1810.

When Kamakahelei died in 1794, she passed their titles and positions to the 16-year-old Kaumualiʻi, who reigned under the regency of Chief Inamoʻo until he came of age.

Over the next years, Kamehameha amassed the largest armada Hawaiʻi had ever seen: foreign-built schooners and massive war canoes armed with cannons to carry his vast army.

The move was supported by Kamehameha as well as the people of Kauaʻi and the foreign sandalwood merchants on the island, whose trade was hurt by the constant feuding.

In 1816, Kaumualiʻi signed an agreement to let Georg Anton Schäffer and his Russian crew build the forts Alexander and Barclay-de-Tolly.

[1] Kamehameha I died in 1819, and the Hawaiians grew fearful that Kaumualiʻi would sever Kauaʻi's relationship with the united Hawaiʻi.

[4]: 138–146  To make the domination clear, Kaʻahumanu forced him to marry her to ensure the island chain's stable union.

Captain George Vancouver, who gave the young king a flock of sheep as a gift in 1792, was thanked with a lavish banquet and described his host glowingly.

[4]: 224 After Kaumualiʻi's death in 1824, his son by sacred wife Kawalu, daughter of Kamakahelei and ali'i Kiha of Ni'ihau,[citation needed] George "Prince" Kaumualiʻi Humehume (1797–1826), also known as George Tamoree, attempted to reestablish the independence of Kauaʻi but was also eventually captured and taken to Honolulu, where he died of influenza.