John Joseph O'Neill (June 25, 1846 – February 19, 1898) was a U.S. Representative from Missouri.

Born in St. Louis, Missouri, O'Neill attended the common schools.

He served as a member of the Missouri House of Representatives from 1872 to 1878.

He served as chairman of the Committee on Expenditures on Public Buildings (Forty-ninth Congress), Committee on Labor (Forty-ninth and Fiftieth Congresses).

He successfully contested the election of Charles F. Joy to the Fifty-third Congress (April 3, 1894 – March 3, 1895).