The Mufti of Jerusalem from 1921 to 1936. During the Mandatory period, Haj was one of the most important Arabs in Palestine. Haj hated both the British and Jewish people, and was a nationalist figurehead for many Muslims in Palestine at that time. He also frequently incited riots against Jewish settlements, and is known to have planned the riots of 1929 and 1936. He met Hitler in 1938 and was thereafter a major Nazi collaborator, recruiting thousands of Croats and Turks into the SS.

Despite his violent anti-semitism, al-Husseini had at least one major project that earned him respect- the restoration of the Dome of the Rock. Not only was the Dome restored to it's former glory, it was fully plated in gold as well. This, in turn, enhanced the status of Jerusalem to Muslims everywhere.

During World War II, the mufti created great amounts of support for Germany among Muslims. He personally met Hitler in November of 1941, however, his notoriety left him when the Arab armies were famously defeated in 1948.