Andrew Sylvester Warner (January 12, 1819 – December 26, 1887) was an American politician from New York.
He was born on January 12, 1819, in Vernon, Oneida County, New York, the son of Andrew Warner (c.1791–1843) and Elizabeth C. (Young) Warner (b. c.1796). In 1837, the family removed to a farm in Sandy Creek, in Oswego County. On October 19, 1842, he married Mary Elizabeth Greene (d. 1859), and they had two sons.
He was a Free Soiler in 1848, and joined the Republican Party upon its foundation. He was a member of the New York State Assembly (Oswego Co., 2nd D.) in 1855 and 1856; and of the New York State Senate (21st D.) in 1860 and 1861.
On October 3, 1861, he married Chloe Monroe (1840–1916), and their son was Wilbert Charles Warner MD (1864–1927). He fought in the American Civil War attaining the rank of colonel, but contracted typhoid fever and was discharged.
In 1874, he ran as an Independent for Congress in the 24th District, but was defeated by Republican William H. Baker.
He died on December 26, 1887, in Sandy Creek, New York; and was buried at the Woodlawn Cemetery there.