His elder brother Benjamin Watkins Leigh had become an attorney practicing in Petersburg, so Leigh went to Williamsburg, Virginia for formal education, but was only able to afford one year at the College of William and Mary (in 1804) so he returned to Chesterfield County to assist his uncle and read law.

They moved to Halifax County, Virginia where Leigh built an estate, Leighwood.

Admitted to the bar in 1805, Leigh practiced law and served as a judge for the Halifax County Court.

He represented Halifax, Charlotte, and Prince Edward Counties in the Virginia Constitutional Convention of 1829-1830.

He was then appointed to the Circuit Superior Court of Law and Chancery and held that position until he retired.