Born near West Liberty, Virginia. Graduate of Ohio University in 1815. Studied law and admitted to the bar in Ohio in 1816. Married Maria Willis Boyle January 7, 1820. They had six children. Three sons, Thomas Jr., Hugh Boyle and Charles, became Union generals. In 1829 his friend and neighbor Judge Charles Sherman died. Ewing informally adopted his son William Tecumseh Sherman and as Senator appointed Sherman to West Point. Sherman married Ewing's daughter Eleanor Boyle Ewing.

Elected to the United States Senate and served 1831 to 1836. Appointed Secretary of the Treasury by President Harrison and reappointed by Tyler. He served March 6, 1841, to September 11, 1841. Appointed Secretary of the Interior by President Taylor and served 1849 to 1850. In 1850 he was appointed again to the Senate to complete the unexpired term of Thomas Corwin who had been appointed Secretary of the Treasury. He served until 1851.

Ewing died in Lancaster, Ohio.

bio: ApCAB; BDC; BDEB; DAB; Drake; NCAB 25; TCBDA; WWWA-H