The 1888 Democratic National Convention was a nominating convention held June 5 to 7, 1888, in the St. Louis Exposition and Music Hall in St. Louis, Missouri. It nominated President Grover Cleveland for reelection and former Senator Allen G. Thurman of Ohio for vice president.

Allen Granberry Thurman, sometimes erroneously spelled Allan Granberry Thurman, was a Democratic U.S. representative, Ohio Supreme Court justice, and Senator from Ohio. He unsuccessfully ran for Vice President of the United States in 1888 with President Grover Cleveland.