'Umar was a supporter of the Abbasid Revolution and fought during the Siege of Wasit. Following the Abbasid victory against the Umayyads, he was appointed to a number of governorships. Under Abu al-'Abbas he was governor of al-Basrah until 750 and was subsequently appointed to al-Bahrayn. Following the ascension of al-Mansur, he was appointed twice more to al-Basrah, from 755 to 757 and from 759 to 760.