The 1900 United States Senate election in Kentucky was held on January 16, 1900, after an initial election on January 9, 1900. Democratic candidate and former senator J. C. S. Blackburn was elected by the Kentucky General Assembly to the United States Senate. The election was held twice due to ambiguity in the law setting the election date.
The Democratic Party chose to select its candidate by legislative caucus. Former senator J. C. S. Blackburn was nominated unanimously by the caucus on January 2, 1900. He had previously been endorsed by the state Democratic convention in June 1899.