Adarnase IV (Georgian: ადარნასე IV) (died 923), or Adarnase II, was a Georgian monarch of the Bagrationi dynasty who reigned in the late 9th and early 10th centuries. The son of the Kouropalates David I of Iberia, he ruled as duke of Lower Tao from 881 to 923, king (mepe) of the Kingdom of the Iberians from 888 to 923 and Kouropalates of Iberia from 891 to 923, re-establishing the Georgian monarchy in 888, more than three centuries after the abolition of the Kingdom of Iberia by Sasanian Empire.
He succeeded his father to the duchy of Lower Tao, a border march between Byzantine Empire and Caucasus, when the latter was assassinated by Nasra of Tao-Klarjeti in 881. When the latter led a Byzantine invasion force to invade the Caucasus, Adarnase defeated him in 888 and became the first sovereign to take the title of ‘King of the Iberians’, to signal his independence from the Byzantine Empire. With the help of neighbouring Armenia, he consolidated his power and gained control over Kartli, as well as Byzantine recognition in 891 after killing Gurgen I of Tao. The reign of Adarnase IV was marked by a change in Georgia's political orientation, as it left the Byzantine sphere of influence to join Armenia and, by extension, a declining Abbasid caliphate. The king often became involved in Armenia's internal affairs and helped King Smbat I of Armenia to consolidate his own power.