In May, 1920, he was named a founding member of the Young Arab () via an amendment made by the original founders to the party constitution. The Young Arab was the largest and most influential Arab party in the late Ottoman period and early independent era. He became an influential figure in the Syrian revolts against the French. In 1920 Atassi took part in establishing The Homs Defense Committee, headed by his cousin Omar al-Atassi. The committee organized armed clashes between the people of Homs and the French troops. He was charged with providing the necessary financial support through donations from both public and governmental agencies. Between 1919 and 1925 he was delegated by the nationalists of Homs to represent them in meetings with the influential families and tribes of the area, such as the Azms, Keilanis and Barazis of Hama, the Suweidans of Hisyah, the Dandachis of Talkalakh, and the Ahsenah tribe. These meetings were held to discuss the struggle for independence and were a prelude to the Syrian Revolution of 1925. He became one of the brains behind the uprisings of the two sister cities of Homs and Hama. In 1925 he joined the Peoples' Party of Abd al-Rahman Shahbandar, along with Shukri al-Jundi, Mazhar Raslan, Shafiq al-Husseini, and Abdul-Kareem al-Droubi, and established a chapter in Homs.