de Wet came from a well to do Dutch speaking Cape family.de Wet attended Leiden University however did not complete his studies, instead obtained his BA degree at the University of London.
He was called to the Inner Temple, London, as a barrister-at-law in June 1863.
Shortly after being admitted as a barrister, he returned to the Cape and six months later, on 14 December 1863, he was also admitted to the Cape Bar.
In April 1882 de Wet and Emma sailed for Colombo, Ceylon, via Calcutta, India.
de Wet assumed his duties as Chief Justice four months after Sir Richard Cayley had left for England, on 31 May 1882.He was knighted in the 1883 Birthday Honours.