Askari served in the Ottoman Empire Army during World War I until he was captured by British forces moving into the Empire from Egypt. After escaping his captors, he fled eastward, where he was converted to the cause of Arab nationalism and joined forces with T. E. Lawrence (Lawerence of Arabia), together with his brother-in-law, Nuri as-Said, who would also serve as prime minister of Iraq. Askari took part in the attack on Damascus and supported placing Faisal on the Syrian throne. When Faisal was deposed by the French, he advocated granting him a new throne in Iraq.
As a reward for his loyalty, Faisal granted Askari several important cabinet positions, including minister of defense in the first Iraqi government. He served as prime minister twice, and was also minister of foreign affairs. Askari was minister of defense in Yasin al-Hashimi's government, when it was overthrown by Chief of Staff Bakr Sidqi in 1936, in Iraq's first coup. Askari was killed in the coup. A relative of Askari later avenged his death by assassinating Bakr Sidqi, together with Ali Jawwad, commander of the airforce, at the Mosul airport.