gillette was born in old windsor, connecticut (today part of the town of bloomfield), gillette moved with his parents, rev. ashbel and achsah francis, to ashfield, massachusetts as a child. he graduated from yale college in 1829 and commenced the study of law, but his health becoming impaired he instead engaged in agricultural pursuits in bloomfield. he was a member of the connecticut house of representatives in 1832, 1836 and 1838 and was an unsuccessful candidate for governor of connecticut in 1841, losing to chauncey f. cleveland, and several times subsequently. gillette served as chairman of the connecticut board of education from 1849 to 1865 and moved to hartford, connecticut in 1852 and later developed the neighborhood, "nook farm" with his brother-in-law, john hooker. he was elected a free soiler to the united states senate in 1854 to fill a vacancy and served until the end of the term in 1855, not being a candidate for reelection. afterwards, gillette became a lecturer on agriculture and temperance and was a trustee of the connecticut state normal school, also serving as its president for many years. he aided in the formation of the republican party in connecticut and for several years was a silent partner in the "evening press", the organ of the party. he engaged in the real estate business in hartford, connecticut until his death there on september 30, 1879. he was interred in riverside cemetery in farmington, connecticut.