John Smith Preston (April 20, 1809 – May 1, 1881) was a wealthy planter, soldier, and attorney who became prominent in South Carolina politics in the 19th century.

An ardent secessionist, he was the state's delegate dispatched to help convince the Virginia Secession Convention to join South Carolina in seceding from the antebellum Union in the months prior to the start of the American Civil War.

Preston was born at "Salt Works," a sprawling estate owned by a prominent military family near Abingdon, Virginia.

He later invested heavily in a sugar plantation, The Houmas, near Baton Rouge, Louisiana, which prospered and gained him substantial wealth.

[3] He was also the state's delegate dispatched to help convince the Virginia Secession Convention to join South Carolina in seceding from the antebellum Union in the months prior to the start of the Civil War.