John Hart Brewer (March 29, 1844 – December 21, 1900) was an American Republican Party politician who represented New Jersey's 2nd congressional district in the United States House of Representatives from 1881 to 1885.

Brewer was the great-great-great grandson of John Hart, a signer of the United States Declaration of Independence.

Born in Hunterdon County, New Jersey, Brewer attended Lawrenceville School and Trenton Academy, and graduated from the Delaware Literary Institute, Franklin, New York, in 1862.

After leaving Congress, he resumed the manufacture of pottery until 1895, when he engaged in the insurance business.

He was appointed assistant appraiser of merchandise at the port of New York City by President McKinley and served until his death in Trenton, New Jersey, December 21, 1900.