After the death of Joseph Oliver Carter, Iaukea became the private secretary and business agent of Liliʻuokalani. From 1909 to 1917, he served in this role and became a trustee of The Queen Liliʻuokalani Trust, a charitable trust established by the queen to manage her landholdings and estate after her death. Iaukea and his wife Charlotte were at Liliʻuokalani's side when she died in 1917. He was the one who raised her royal standard (flag) over Washington Place to signal her death, and was in charge of planning Liliʻuokalani's state funeral. He served as an honorary pallbearer during the funeral procession while his son Frederick Hank Iaukea served as an active pallbearer carrying the catafalque bearing the casket of the queen to her final resting place for entombment with her family members in the Kalākaua Crypt of the Royal Mausoleum of Mauna ʻAla. As a former chamberlain, and one of the last surviving representatives of the former dynasty, he had planned the royal funerals of Princess Kaʻiulani in 1899, Prince David Kawānanakoa in 1908, and Prince Jonah Kūhiō Kalanianaʻole in 1922. He was chairman of the Hawaiian Homes Commission from 1933 to 1935, member of the Archives Commission from 1937 and custodian of the throne room of Iolani Palace from 1937.