Following the war, he began a literary career in both Yiddish and Hebrew, publishing poems, short stories, and reflections in local Jewish publications.

In 1919, his story "Amongst the Evening Shadows" ("בין צללי ערב") was published in the Odessa-based magazine Mashuat ("משואות"), edited by Moshe Glikson (later the editor of Ha'aretz newspaper).

By 1922, he moved to Berlin, where he became active in the left-wing Zionist organization Poale Zion and began to work full-time as a writer and translator.

In 1924, Yeivin was hired by the Histadrut, the largest Jewish trade union in Palestine, to work as a teacher in the Jezreel Valley.

From then on, Yeivin became one of the main thinkers of Revisionist Maximalist ideology, a far-right variant of Zionism which took inspiration from the militant practices of Italian fascism.

He was hired by Ze'ev Jabotinsky to contribute to Doar Ha'Yom (דאר היום), a daily founded by Itamar Ben-Avi.

[4] Following the 1929 Palestine riots, in 1930, Ahimeir, Greenberg, and Yeivin founded Brit HaBirionim (ברית הבריונים), a clandestine, militant, and self-declared fascist group.

Brit HaBirionim sought to overthrow British rule in Palestine and establish a Jewish state based on nationalist, integralist principles.

[5] The group participated in several actions, mostly anti-British in nature, including organizing protests against the British-led census and against visits from British officials.

[2] In 1939, he began to write broadcasts for the Irgun-led radio station, Kol Zion Ha'Lochemet (קול ציון הלוחמת), alongside Avraham ("Yair") Stern and David Raziel.

He published short stories and political essays, which called for the establishment of a Jewish state based on Biblical borders, in the monthly journal Solam (סולם).