Rostom was a son of Mamia I Gurieli by his wife Ketevan. In 1533, Mamia was taken captive during his disastrous expedition against the Circassians in which Rostom's brother Giorgi was killed. Rostom had to ransom his father, on whose death he succeeded as Prince of Guria a year later. By that time, Guria, a principality on Georgia's southwestern Black Sea coast, had been menaced by the resurgent Ottoman Empire, then being in war with Safavid Persia over hegemony in the Caucasus. Rostom stood by the side of his official royal suzerain, King Bagrat III of Imereti, in his struggle against the Ottoman encroachment.
Ottoman wars
In 1535, Rostom joined forces with Bagrat in an invasion of the Principality of Samtskhe, ruled by the pro-Ottoman atabagQvarqvare III Jaqeli. At the battle of Murjakheti, the atabag was defeated, captured by Gurieli's cup-bearer Isak Artumeladze, and eventually delivered to Bagrat. Qvarqvare died in prison, while Rostom was awarded his share of Samtskhe: Adjara and Chaneti, long sought after by the Gurieli dynasty. The Ottomans retaliated with a major invasion: Bagrat and Rostom were victorious at Karagak in 1543, but decisively defeated, in 1545, at Sokhoista, where Rostom's son Kaikhosro was killed. In 1547, the Ottoman military imposed a blockade of Guria's coastline and occupied the maritime settlements of Gonio and Batumi. Rostom appealed for help to Bagrat of Imereti and Levan I Dadiani, Prince of Mingrelia. However, the king of Imereti, indignant at Rostom's earlier decline of a combined attack on Mingrelia, disrupted the nascent Dadiani–Gurieli accord. Left to his own devices, Rostom attacked, pushed the Ottoman forces beyond the Chorokhi and forced them to evacuate Batumi, but he failed to prevent the loss of Adjara and Chaneti; the Gonio fortress became an important Ottoman outpost in southwestern Georgia. Rostom died in 1564 and was buried at the Shemokmedi Monastery. He was succeeded by his son, Giorgi II Gurieli.
Family
Rostom Gurieli was married twice, first to Princess Tinatin, a member of the Imeretian royal family, and secondly, to Princess Tamar. He fathered three sons and two daughters: