“Day in Commemoration of Kamehameha I,” (La Ho‘o-mana‘o o Kamehameha I) was first celebrated in 1871, on December 11 (Kamehameha V’s birth date.) Because the weather is better in the summer, the decision was made to move the celebration six months earlier (i.e. June 11 – the date has no direct significance to Kamehameha I.)
The 1896 legislature declared it a national holiday. In 1939, Hawaiʻi Revised Statutes under the Territorial Legislature of Hawai‘i created the King Kamehameha Celebration Commission – that law remains in effect, today. In 1978 the legislature renamed this holiday King Kamehameha I Day.