When he was about seventeen years old he went to that part of Lunenburg County later organized as Charlotte County, to study law with Clement Read, county clerk and a man of wealth, culture, and influence. He lived in his instructor's home.
Carrington began the practise of law when twenty-one years old, and was very successful. Fortunate family connections and his own ability brought many appointments his way. He was king's attorney of the counties of Bedford, Mecklenburg, Botetourt, and Lunenburg; was major of the Lunenburg militia; and when a portion of Lunenburg County was separated therefrom and organized as Charlotte County in 1765, was chosen as one of its representatives in the Colonial General Assembly, a position which he retained throughout the life of that body. He was also county lieutenant and presiding justice of Charlotte County. In spite of these numerous positions under the crown, he was ever loyal to the Colony.
He voted for the resolutions instructing Virginia's delegates in Congress to propose independence. After representing Charlotte in the state Senate during the first two years of its existence, he began his long career on the bench as a member of the general court (created in 1779). In 1780 he was made chief justice of that body. When the new court of appeals was created in 1789, Carrington was made one of the five judges, and was continued in that position until his resignation in 1807. At that time he retired to private life after having held public office without intermission for forty-two years. The last years of his life were spent at "Mulberry Hill" on the Staunton River.
He remained active and erect until within a year of his death, which occurred at the age of eighty-five.
He was a member of the Mercantile Association of 1770;
In the Virginia convention of 1776 he was a member of the committee which reported the Declaration of Rights and the Virginia Constitution of 1776. He was a member of the Committee of Safety (both the first and second groups) which was the revolutionary executive body in Virginia until the formation of the state government in July 1776.
He was vigorous in body, "over six feet in height, with prominent features, bright blue eyes, and sandy hair".
He married Clement Read's daughter, Margaret. In his sixtieth year he had married Priscilla Sims, his first wife having died in 1766.