At a young age, Kekaʻaniau was chosen to attend the Chiefs' Children's School (later renamed the Royal School) taught by American missionaries and declared eligible to succeed to the Hawaiian throne by King Kamehameha III. She married American businessman Franklin Seaver Pratt and became known as Mrs. Pratt. Five of her classmates became reigning monarchs of Hawaii until the 1893 overthrow of the Kingdom of Hawaii. In 1920, she wrote "History of Keoua Kalanikupuapa-i-nui: Father of Hawaii Kings, and His Descendants", a book about her ancestor Keōua and his descendants including her own branch of the family and the House of Kamehameha. Outliving all her royal classmates, she was the last surviving member of the Royal School.