Sultan Ahmad Khan Mohammadzai, was the ruler of the Emirate of Herat from 1857 to 1863. In 1855-56, Sultan Ahmad Khan sent a petition to the Shah of Iran, Naser al-Din Shah Qajar. If the Iranians would support Sultan Ahmad Khan with an army, he would overthrow his uncle Dost Mohammad Khan and incorporate Afghanistan into the Guarded Domains of Iran. However, Sultan Ahmad Khan was intercepted by Dost Mohammad Khan, who exiled Sultan Ahmad Khan to Iran. in accordance with the Treaty of Paris. During Sultan Ahmad Khan's reign, he was completely dependent on Iran and not only minted coins in the Shah's name, but also given assistance against the Mohammadzais to the east.
He captured Farah soon after in March 1862, which had been a Mohammadzai possession since their occupation of the town on October 30, 1856. Farah was captured by the Mohammadzais. On July 22, being succeeded by his son Shah Nawaz Khan. Shortly before his death, he had been affected by a disease that causes limb paralysis.