In 1935, he was assigned the post of caretaker of a Muslim shrine in Haifa, and during his residence there, he came into contact with the Syrian revolutionary Izz ad-Din al-Qassam who was leading an insurgency against British forces in Palestine.

Shawwa was appointed by Egyptian president Muhammad Naguib to "cleanse" Gaza of corruption and any remnants of the monarchy of Farouk of Egypt.

[1] He took over responsibility for the management of the municipality and made the decision to not annex adjacent Palestinian refugee camps to the city such as al-Shati and Jabalia.

He commenced the development of the economic sector in the Gaza Strip, working on major projects for the export of locally grown citrus to the Arab world, and establishing a juice factory which still exists off Salah al-Din Street.

[1] During the First Intifada, Shawwa publicly sympathized with the participants of the uprising, saying "People here have reached a point where they don't see much difference between life and death under the insulting and degrading conditions of military occupation."