Smith was a veteran of the American Revolutionary War and later graduated from Princeton University, then known as the College of New Jersey.

During the American Revolutionary War, Smith enlisted as a private in the Continental Army, later participating in the Battle of Brandywine.

[1] As a legal expert in admiralty law, Thomas Jefferson appointed him as Secretary of the Navy in July 1801, after William Jones declined the position.

[1] On March 2, 1805, the Senate confirmed the appointments of Smith as United States Attorney General and Jacob Crowninshield as Secretary of the Navy.

[1] During his time as Secretary of State, Smith pursued an assertive policy to claim the Spanish-controlled West Florida.

[3] In October 1810, Smith lied to General Louis Marie Turreau, claiming the United States would not support rebellion in the territory.

Madison offered Smith the post of Minister to Russia, which was currently held by John Quincy Adams.

In 1818, he became the founding president of the Maryland Agriculture Society and afterwards retired to a more private life where he enjoyed his wealth.