[2] Al-Tamimi served in the local administration of the Ottoman Empire as a principal of a government-run school in Beirut.

[2] Despite working for the Ottoman government, in 1911, while in Paris, he and his colleague Awni Abd al-Hadi founded the underground organization, al-Fatat, which called for Arab independence from the empire.

[3] In 1916, during World War I, Ottoman officials ordered al-Tamimi to gather information for a general "guide book" on the southern half of the Beirut Province, namely Jabal Nablus.

In July 1919, following the Arab Revolt (1916–18) which succeeded in gaining Arab independence, al-Tamimi along with Izzat Darwaza, Sa'id Haydar and other members of al-Fatat's inner circle formed a group in the Syrian National Congress that rejected the establishment of any foreign mandate (British or French) in the region of Syria, claiming it would only be a "disguised form of imperialist penetration.

[7] He led efforts to merge the al-Najjada and al-Futuwa youth movements in Palestine in 1946.