Ingersoll was a member of the State house of representatives 1820-1825 and served as speaker during the last two years. He was elected as an Adams candidate to the Nineteenth and Twentieth Congresses and reelected as an Anti-Jacksonian to the Twenty-first and Twenty-second Congresses (March 4, 1825 - March 3, 1833). He was not a candidate for renomination in 1832. He resumed the practice of law and was later appointed State’s attorney for New Haven County in 1833. He declined the appointment as United States Senator tendered by Governor Edwards upon the death of Senator Nathan Smith in 1835. He was Minister to Russia from August 8, 1846 until July 1, 1848, when he resigned. He again engaged in the practice of law and was mayor of New Haven in 1851. He died 1872 and was buried in Grove Street Cemetery.