James H. Knowlton (August 22, 1813 – January 29, 1879) was an American politician and lawyer.

His brother, Wiram Knowlton, was a justice of the Wisconsin Supreme Court.

[1] At Shullsburg he completed his legal studies, was admitted to the bar, and served as the first probate judge of the county.

[1] He was a member of the legal team defending Judge Levi Hubbell during his 1853 impeachment, and later that year was elected to the Wisconsin State Assembly as a Democrat.

[1] After the 1856 legislative session, Knowlton moved back to Janesville, in Rock County, where he was elected to his third and final Assembly term in 1857.