John Gaines Miller (November 29, 1812 – May 11, 1856) was a U.S. Representative from Missouri.
Born in Danville, Kentucky, Miller attended the common schools and was graduated from Centre College in Danville.
He served as a member of the state house of representatives in 1840.
Miller was elected as a Whig to the Thirty-second and Thirty-third Congresses and reelected as an Opposition Party candidate to the Thirty-fourth Congress, and served from March 4, 1851, until his death near Marshall, Missouri, May 11, 1856.
He was interred in Mount Olive Cemetery, near Marshall, Missouri.