Abdul Illah was the brother of King Ghazi, and was regent of Iraq for King Faisal II from April 4, 1939 to May 2, 1953, when Faisal came of age. He also held the title of Crown Prince of Iraq from 1943.

A son of Ali ibn Hussein of Hejaz, he assumed power upon the death of his brother in an automobile accident. He was deposed briefly by former prime minister Rashid Ali al-Kaylani, who led a pro-German coup during World War II but was restored after the United Kingdom invaded the country in May 1941.

Abdul Illah stepped down in 1953, when Faisal came of age, but he continued to be a close adviser of the young king, and an advocate of a pro-Western foreign policy. He was killed, along with most of the royal family, on July 14, 1958, in a coup that brought an end to the Iraqi monarchy.