The Barmakid family was an early supporter of the Abbasid revolt against the Umayyads and of As-Saffah. This gave Khalid bin Barmak considerable influence, and his son Yahya ibn Khalid (d. 806) was the vizier of the caliph al-Mahdi (ruled 775–785) and tutor of Harun al-Rashid (ruled 786–809). Yahya's sons al-Fadl and Ja'far (767–803), both occupied high offices under Harun.

Many Barmakids were patrons of the sciences, which greatly helped the propagation of Iranian science and scholarship into the Islamic world of Baghdad and beyond. They patronized scholars such as Gebir and Jabril ibn Bukhtishu. They are also credited with the establishment of the first paper mill in Baghdad. The power of the Barmakids in those times is reflected in The Book of One Thousand and One Nights the vizier Ja'far appears in several stories, as well as a tale that gave rise to the expression "Barmecide feast".

In 803, the family lost favor in the eyes of Harun al-Rashīd, and many of its members were imprisoned.