John James Gardner (October 17, 1845 – February 7, 1921) was an American Republican Party politician who represented New Jersey's 2nd congressional district in the United States House of Representatives for ten terms from 1893 to 1913, and was Mayor of Atlantic City, New Jersey.

At the time of his election to Congress, Gardner was the longest serving member in the history of the New Jersey Senate, having represented Atlantic County for five consecutive terms from 1878 to 1893.

He served as member of the common council and coroner of Atlantic County in 1876.

In April 1898, Gardner was among the six representatives who voted against declaring war on Spain.

He was an unsuccessful candidate for reelection in 1912 to the Sixty-third Congress and resumed agricultural pursuits.