Alexander was born sometime after 1358 into the family of Bagrat I, then duke (and ex-king) of Imereti, and his wife, a Jaqeli atabeg of Samtskhe. On his father's death in 1372, Alexander was appointed by King Bagrat V of Georgia as duke of Imereti. In 1387, he took advantage of Timur's invasions of Georgia and proclaimed himself king of Imereti at the Gelati Monastery, but the city of Kutaisi remained in the hands of Bagrat V's loyalists and the dukes of Mingrelia, Guria, Abkhazia, and Svaneti refused to join him. Alexander succeeded in seizing several fortresses in Imereti, but Kutaisi remained outside his control. He died in 1389 and was succeeded by his brother George I.