Mohammad Khan Tokhmaq Ustajlu (Persian: محمد خان تخماق استاجلو‎, romanized: Mohammad Xān Toxmāq Ostājlu), also commonly known as Tokhmaq Khan Ustajlu (Persian: تخماق خان استاجلو‎), was a 16th-century Safavid official, diplomat and military leader from the Turkoman Ustajlu tribe. He was appointed as governor (beglarbeg) of Erivan Province (also known as Chokhur-e Sa'd) in 1568–1575. Thereafter, he led an embassy to the Ottoman Empire. On his return, he participated in some judicial developments, and was reappointed as governor of Erivan Province in 1578. In the same year, he served as main commander at the Battle of Çıldır during the Ottoman–Safavid War of 1578–1590, where his army was routed. A few years later, in 1583, Mohammad Khan Tokhmaq's second tenure over the Erivan Province was bro