He was military secretary to General Andrew Jackson during the First Seminole War in 1818. In 1820 he settled in Florence, Alabama and became county judge in 1822. In 1829 the new President Jackson appointed him as Secretary of the Arkansas Territory. Fulton moved to Little Rock and took up his new responsibility.
He served as Secretary until 1835, when he was appointed Governor of the Territory. When Arkansas was admitted as a state in 1836 he became one of its first Senators. In the Senate he became a member of the Democratic Party. Fulton remained a Senator until his death in 1844. He died at home in Little Rock and is buried in the historic Mount Holly Cemetery in there. Fulton County, Arkansas is named for William Savin Fulton.