Thomas B. Mitchell (died 1876) was an American lawyer and politician from New York.
He practiced law in Canajoharie.
He was a member of the New York State Senate (6th D.) from 1843 to 1846, sitting in the 66th, 67th, 68th and 69th New York State Legislatures. He was a delegate to the 1844 Democratic National Convention in Baltimore.
Afterwards he removed to Schenectady. He was Tempoarary Chairman of the Hard-Shell Democratic state convention, held in July 1854 at Syracuse.
Congressman William Mitchell (1807–1865) was his brother.