It is not known when Zhou Yunyuan was born, but it is known that he was from Yu Prefecture (豫州, roughly modern Zhumadian, Henan).
He became deputy imperial censor reviewing central government affairs (左肅政中丞, Zuo Suzheng Zhongcheng) in early 694, and in winter 694 Wu Zetian made him acting Fengge Shilang (鳳閣侍郎), the deputy head of the legislative bureau of government (鳳閣, Fengge).
She also gave him the designation of Tong Fengge Luantai Pingzhangshi (同鳳閣鸞臺平章事), making him a chancellor de facto.
Soon thereafter, Zhou and the assistant chief judge of the supreme court Huangfu Wenbei (皇甫文備) submitted articles of impeachment against five chancellors -- Doulu Qinwang, Wei Juyuan, Du Jingjian, Su Weidao, and Lu Yuanfang, of being unable to curb the powerful chancellor Li Zhaode, whom Wu Zetian exiled in late 694.
On one occasion, when Wu Zetian held a feast for the chancellors, she asked them to quote good passages from books.