John O'Connor PC (January 1, 1824 – November 3, 1887) was a Canadian politician and cabinet minister.

Born in Boston, Massachusetts, the son of Irish immigrants John and Mary O’Connor, he moved with his family to Essex County, Upper Canada in 1828.

He was re-elected to the 2nd Canadian Parliament but was defeated in the 1874 federal election.

In the period of 1872 to 1873, he was President of the Privy Council, Minister of Inland Revenue, and Postmaster General.

In 1884, he was appointed a judge of the Court of Queen’s Bench for Ontario.