Running as a member of the Hawaiian National Party, Baker was elected to the House of Representative, the lower house of the legislature of the kingdom. He sat in on the legislative assembly of 1886 and 1890. King Kalākaua appointed him as high sheriff of the Island of Hawaii in 1886 at the time of his wife's appointment as Governess. He also served as a member of the Privy Council of Kalākaua and his successor Queen Liliuokalani. On March 14, 1891, he was appointed to the staff of Queen Liliuokalani and was elevated to the rank of Colonel. The Royal Governorship of Hawaii Island held originally by his wife Ululani had been abolished by the legislature after the Bayonet Constitution. In 1892, Liliuokalani revived this political position and appointed Baker as Governor of the Island of Hawaii. He served from February 8, 1892 to February 25, 1893. After the overthrow of the Kingdom of Hawaii, the Provisional Government of Hawaii passed an act abolishing the island governorships again; this act passed on February 27 and went into effect on February 28. Baker was an anti-annexationist.