Prince Mansour's first government post was the supervision of the royal palaces in Riyadh which he was appointed in 1938. In 1940 he was made minister of war. In 1942 Prince Mansour participated King Abdulaziz's meeting with the British ambassador in Riyadh. Prince Mansour was also the emir of Murabba Palace in 1943. He officially visited Cairo when King Abdulaziz sent him there to support the Indian Muslim officers and men just before the Battle of El Alamein. Prince Mansour also acted as an aide to Prince Faisal during the latter's post of viceroy of Hijaz.