Thomson F. Mason was a grandson of George Mason of Gunston Hall, who lived from 1725-1792. George Mason wrote the Virginia Declaration of Rights, one of the most influential documents on human rights in American history, and petitioned to have the Bill of Rights added to the U.S. Constitution to safeguard the rights of individuals. Although George Mason helped draft the U.S. Constitution, he refused to sign it because of its compromises on slavery and other issues.

Thomson was born in 1785 at Gunston Hall and grew up on his father's estate, nearby Hollin Hall. His parents were Sarah McCarty Chichester and General Thomson Mason (1759-1820), an officer of the militia in the American Revolution. General Mason held many state and local offices and was active in organizing banks and transportation companies.

Young Thomson attended Princeton University, graduating with honors in 1807, after which he returned to Northern Virginia to establish himself as a lawyer.  He married Elizabeth (Betsey)

Clapham Price of Loudoun County in 1817, and they had eight children.

Thomson F. Mason became one of the area's most prominent lawyers and played an important role during the 1820's in the fight to separate Alexandria from the District of Columbia. As he became increasingly involved in political activities, he served on the Alexandria Common Council eight times, was elected mayor of Alexandria three times and served three terms as justice of the peace. Only six months before his death in 1838, he was appointed the first judge of the new Criminal Court of the District of Columbia.

He devoted much of his career to helping Alexandria recapture some of its past prosperity and establish itself as a major commercial center. To promote and facilitate commerce, Mason served as president of both the Middle Turnpike Company, which developed present-day Route 7, and the Alexandria Canal Company, working for an extension of the C&O Canal. Mason is buried at the Christ Church Cemetery on Wilkes Street in Alexandria.