His father was the Colonel Robert William Kalanihiapo Wilcox who had led a failed rebellion to reestablish the Kingdom of Hawaii. Born in 1893 a few days after the overthrow of the Hawaiian Kingdom, his younger sisters were Princess Virginia Kahoa Kaahumanu Kaihikapumahana Wilcox and Princess Elizabeth Ka'akaualaninui Wilcox, and his half sisters were Princess Daisy Emaline Napulahaokalani Cartwright and Princess Eva Kuwailanimamao Cartwright. His name Kalanikupuapaikalaninui Keoua, states his and his family's descent from High Chief Keoua Kalanikupuapaikalaninui the royal father of Kamehameha the Great and Kalokuokamaile, great-great-great grandfather of Robert.
He married his first wife, Helen Kaleipuanani Simerson Wilberton, daughter of William Kuakini Simerson, by his wife, Julia, née Andrews, on 15 April 1916. His second wife was Ruth Ewaliko. He had seven children:
He died in Honolulu, Oahu, 26th February 1934, at age 41.