On April 27, 1864, Pratt married High Chiefess Elizabeth Kekaʻaniau Laʻanui, a great grandniece of King Kamehameha I, being a great granddaughter of Kalokuokamaile, the older brother of Kamehameha I [REF].
The couple did not have any children of their own, although they adopted her niece, Theresa Owana Laʻanui, daughter of her brother Gideon Kailipalaki Laʻanui II, when he died in 1871.