Wei Fangzhi's grandfather Wei Yunqi had served as an official both during the early Tang Dynasty and Tang's predecessor Sui Dynasty, but was killed in 626 shortly after the coup known as the Incident at Xuanwu Gate—as his superior Dou Gui, with whom he had a poor relationship, suspected him of being an associate of Li Jianchengthe Crown Prince, who had been killed during the incident by his brother Li Shimin the Prince of Qin. Wei Fangzhi's father Wei Shishi subsequently served as a Tang official as well, and by the time of Emperor Ruizong's first reign was prefect of Hua Prefecture and deputy head of the household of the crown prince Li Chengqi, with the title of Duke of Fuyang.
Not much is known about the early part of Wei Fangzhi's own career. By 684, he was serving as Luantai Shilang, the deputy head of the examination bureau of government, when Emperor Ruizong's powerful mother and regentEmpress Dowager Wu moved him to the post of Fengge Shilang, the deputy head of the legislative bureau and also gave him the designation of Tong Fengge Luantai Pinzhangshi, making him a chancellor de facto. In 685, she gave him the more honorific designation of Tong Fenge Luantai Sanpin. Wei Fangzhi served as chancellor for the next several years, but his acts were largely unrecorded in history. An exception was in 687, when Empress Dowager Wu wanted to commission his fellow chancellor Wei Daijia to attack Tufan. Wei Fangzhi, pursuant to the usual protocol, requested that a censor be made the auditor for the campaign. Empress Dowager Wu, however, rejected his request, pointing out that an auditor often served to interfere with the authority of the commanding general, and therefore did not commission an auditor for the campaign. It was also recorded that around that time, Empress Dowager Wu had a large body of administrative regulations drafted, known as the Chuigong Regulations, and that Wei Fangzhi was instrumental in editing the regulations to make them appropriate and was praised for it. By spring 690, Empress Dowager Wu's nephews Wu Chengsi and Wu Sansi had become very powerful, and even the chancellors had to bow to them. When Wei Fangzhi suffered an illness that year, Wu Chengsi and Wu Sansi went to visit him, but Wei lay on his bed and did not answer their greetings. When someone warned him that not doing so risked offending them, he responded, "Life and death are all determined by heaven. How can a real man prostrate himself to flatter imperial relatives just to avoid disaster?" Soon, Wei was falsely accused by Empress Dowager Wu's trusted secret police official Zhou Xing, and he was exiled to Dan Prefecture, and his assets were seized. Later that year, after Empress Dowager Wu had taken the throne from Emperor Ruizong and become "emperor" of her own Zhou Dynasty, Wei was executed in exile. Only after Wu Zetian herself was overthrown in 710 and replaced by Emperor Ruizong's brother Emperor Zhongzong were Wei's honors posthumously restored.
