In 1877, Cleghorn and Princess Likelike arranged to donate the land surrounding the monument to Captain James Cook on Kealakekua Bay marking the site of his death, in trust to the government of the United Kingdom.

He acted as the Royal Governor of Oʻahu in July 1887, and was appointed to succeed Prince Consort John Owen Dominis upon his death in November 1891, until February 28, 1893.

[8] Historian Ralph Simpson Kuykendall noted that "Governor Cleghorn's meager diary for the early part of 1893 suggests the picture of an anguished father frantically trying to save his beloved daughter from the unhappy fate which had befallen her through no fault of her own.

"[11] Cleghorn took an oath of allegiance under protest to the Provisional Government of Hawaii led by Sanford B. Dole in order to retain his position as Collector General of Customs.

[12][13] Cleghorn also helped the new government in enforcing the oath of allegiance with existing governmental employees at the custom house and signed his letter to his superior with "Your obedient servant".

[14] In 1878 Cleghorn sold his residence in Honolulu and moved his family to ʻĀinahau, an estate in Waikiki built on land gifted by Princess Ruth Keʻelikōlani to his daughter Kaʻiulani.

Cleghorn also purchased an adjacent beachfront lot on which was located a stone to which Likelike and Kaʻiulani offered lei and prayers before bathing in the sea.

However, the territorial legislature, reluctant to manage the property, used a specification that the park would have to close each night at 6:00PM as a technicality to refuse the gift.