From 1887 to 1890 he served as the 34th Lieutenant Governor of Massachusetts under Governor Oliver Ames. For significant portions of 1888 and 1889 Brackett served as acting governor due to Ames's illness, notably representing the state in that capacity at the celebration of the centennial of Ohio's settlement, and at the dedication of the Pilgrim Monument at Plymouth. In 1889, when Ames retired, Brackett ran to succeed him. He was supported within the party by a coalition of Blaine supporters (opposed by Mugwumps) and the liquor lobby. He won the party nomination by bypassing its main power brokers, Senators Ebenezer Rockwood Hoar and Henry L. Dawes, engaging instead in local ward level politicking. His victory in the general election, with just 48% of the popular vote, was one of the worst showings of any Republican governor in the state to date.