On January 8, 1808, Fulton married Harriet Livingston (1786–1824), the daughter of Walter Livingston and niece of Robert Livingston, prominent men in the Hudson River area, whose family dated to the colonial era. Harriet, who was nineteen years his junior, was well educated and was an accomplished amateur painter and musician. Together, they had four children.
Five days later, he stole a car and drove to Atlanta, where he boarded a bus and arrived in Tallahassee, Florida, on the morning of January 8. He rented a room under the alias Chris Hagen at the Holiday Inn near the Florida State University (FSU) campus.