Frederick William Seward (he went by Fred in close circles) was born July 8, 1830 to William Henry Seward and Frances Adeline Seward (née Miller) in Auburn, New York. He was the second of five children. His siblings were Augustus Henry Seward, William Henry Seward Jr., Cornelia Seward (who died in infancy), and Frances Adeline Seward.

Fred graduated from Union College in Schenectady, New York in 1849, studied law, and was admitted to the New York State bar in 1851. Besides law, Fred was an editor and owner of the Albany Evening Journal from 1851 to 1861. On November 9, 1854, Fred married Anna M. Wharton. The couple lived in Albany, New York and later Montrose, New York. They never had children.

Fred was appointed Assistant Secretary of State on March 6, 1861 and served in this position until March 4, 1869. On April 14, 1865, Fred and his father were severely injured by Lewis Powell in the same coordinated attack that killed Abraham Lincoln. He survived the attack however and was reappointed to Assistant Secretary of State on March 21, 1877. He served in the position this time until October 31, 1879. Fred passed away on April 25, 1915 and is buried with his family in Fort Hill Cemetery in Auburn.