Born in Charleston, South Carolina, Pinckney attended private schools.
He studied law and was admitted to the bar and commenced practice in Charleston.
Pinckney served as a member of the South Carolina House of Representatives (1816–1832).
[1] In 1838, he won among a field of four candidates with the following votes: Pinckney (600), Col. James Lynah (575), Dr. Joseph Johnston (203), and Dr. J.W.
He was an unsuccessful candidate for renomination in 1836, having been labelled a "traitor" by ultra-conservative Southerners for compromising with New York's Martin van Buren on the 1836 "gag-rule" bill.