Benjamin Jennings Seward (he went by Jennings in close circles) was born on August 23, 1793 to Samuel Sweezey Seward and Mary Seward (née Jennings) in Newfoundland, NJ. He was the eldest of six children. His siblings were Elizabeth Seward (who died as a child), Edwin Polydore Seward, William Henry Seward, Louisa Cornelia Canfield (née Seward), and George Washington Seward.

Jennings married Marcia Armstrong on May 17, 1819. The couple had four children, Augustus Seward, Aurelia Seward (who died as a child), Benjamin Jennings Seward Jr. (who died in infancy), and Clarence Armstrong Seward. His family lived in Kingston, NY for some time in the 1820’s.

Jennings traveled extensively throughout the 1830’s helping to find Sunday Schools in parts of the midwest. By 1836 though, he had moved to Westfield, NY where he served as an agent for the Holland Land Company along with his brother, William.

Jenning’s first wife died in 1839, and he later married Mary Louisa Mumford on January 6, 1841 in New York City. Jennings died a few weeks after his second marriage on February 24, 1841 in his father’s home in Florida, NY. He and his second wife had no children.