Thomas Hoomes Williamson was born on August 30, 1813 in Richmond, Virginia to Thomas and Anne Walke Williamson. He spent most of his childhood in Norfolk, Virginia, where he received his early schooling. He entered the United States Military Academy at West Point, New York in 1829, but resigned in 1833 before receiving his degree.

In 1834 Williamson entered the profession of civil engineering and was the assistant to the United States Engineer in charge of building the dry dock at the Norfolk Navy Yard.

Williamson married Louisa Henrietta Fenton Garnett on May 11, 1837 and the couple had five children: Mercer, William, Anne, Thomas, and Olympia.

In 1841 Williamson accepted a faculty appointment at VMI where spent the remainder of his career except for a brief absences during the Civil War. He taught tactics, drawing, and engineering, and at various times was assigned additional duties (e.g., Commandant of Cadets, Treasurer, and Librarian). While at VMI he wrote a textbook titled "An Elementary Course of Architecture and Civil Engineering."

Williamson took on various special assignments during the Civil War. In April 1861 he served with the Confederate Engineers Corps and worked on the defenses of the Rappahannock River and Manassas, Virginia. In October of that year he was ordered to return to VMI to teach civil and military engineering, but he was recalled to the Confederate Army in April 1862 for temporary special duty on the staff of General Stonewall Jackson.

In 1864 Williamson married for the second time to Julia Wharton (Lewis) and the couple had two children: Sydney Bacon and Cornelia.

Williamson continued his teaching career at VMI until shortly before his death on March 31, 1888.