He served as the Hawaiian consul for the Pacific States of California, Nevada, Oregon, and Washington around the time of the overthrow of the Kingdom of Hawaii in 1893.

At the time of his death in 1898, he had one brother and four sisters (including the widow of Hawaii businessman Charles Brewer II) who survived him.

He later assumed the agency of the Phoenix Guano Islands Company, which he held for seven or eight years, and gained considerable amount of wealth from this venture.

[5][9][10][11] These descendants continue to claim to be the rightful successors of the Kamehameha line and claimant to the Hawaiian crown lands through Kekaʻaniau's status as the last surviving member of the Royal School.

In order to quell the civil disruption, American and British troops were landed with the permission of the Hawaiian government, and the rioters were arrested.

According to an 1876 letter by Emma to her cousin Peter Kaʻeo, Pratt played a role in spreading false rumors that King Kalākaua had contracted leprosy.

In this post, he acted as the Hawaiian Kingdom's diplomatic and commercial representatives for the Pacific States of California, Nevada, Oregon, and Washington.

[1][24] On March 28, 1891, Queen Liliuokalani granted Mr. Pratt a Knight Commander of the Royal Order of Kalakaua in the Blue room of Iolani Palace.

[25] On January 17, 1893, the Hawaiian monarchy was overthrown and the Provisional Government was established until a treaty of annexation could be ratified by the United States Congress.

At the same time, he also lodged a protest against the Provisional Government in the San Francisco Chronicle, a local California newspaper, signing himself as "Hawaiian Consul-General".

[27][28] Because of these actions, Pratt was removed, on March 28, from his office as Consul by Dole and the Executory and Advisory Council of the Provisional Government.

[1] The Hawaii Holomua Progress reported on the last hour of the deceased businessman and the effect on his surviving relatives and friends: It was not an unexpected event which happened, yesterday afternoon, when the death of Mr. Frank S. Pratt, a well known citizen was announced, yet, for ail the weeks of preparation which the loving family and friends had had in which to steel their feelings against the inevitable victory of the fell destroyer, there were no dry eyes around the bedside of the departed when the result was evident.

The deceased who had resided for nearly half a century in this country was a man who, to the fullest extent, possessed the confidence of the whole community foreigners and Hawaiians alike.