He was the son of the Commandant-general and David Johannes Joubert was born on 7 November 1849 in Lichtenburg. He was a veldcornet for the Boven-Vaalrivier district Middelburg under Vecht general Nicolaas Smit at the battle of Majuba. After the war he was appointed veldcornet of this ward. In April 1885 he was appointed commandant of the Ermelo district. Three years later he resigned this post and moved to Carolina district and a year later he was again appointed as relieving commandant. He was also chosen as a member of the Volksraad and in 1898 he resigned as commandant.
At the break out of the war he was selected as a commandant under assistant commandant-general S.W. Burger for the Carolina commando.
In January 1900 he was appointed as vecht-general but resigned because of illness and in May was the last time he was at the Volksraad.
He returned to the Natal border as a vecht-general and was in this position till the end of the war.
He died on 13 March in German southeast Africa from fever