It is not known when Wang Yu was born. He was a fifth-generation descendant of Wang Fangqing, who served as a during the reign of Wu Zetian. His intervening ancestors' names were recorded as Wang Jiao , Wang Chong , Wang Zhonglian , and Wang Shao , none of whom was recorded to have carried any official titles except for Wang Zhonglian, who served as a secretarial officer at Yang Prefecture . Wang Yu himself was said to be well-studied in the worshipping of gods and spirits and particularly paid attention to the proper times to offer sacrifices.
During Emperor Xuanzong's reign
Toward the end of the ''Kaiyuan'' era of Wu Zetian's grandson , Emperor Xuanzong was paying great attention to Taoist doctrines and ceremonies. Wang Yu made a submission to Emperor Xuanzong requesting that an altar, to be called the Spring Altar , be built to the east of the capital Chang'an and dedicated to the Blue Emperor . Emperor Xuanzong agreed, and he made Wang an official-scholar at the ministry of worship and an imperial censor , as well as a special emissary of worship . It was said that Wang drew favors from the emperor due to his dedication to worshipping gods on Emperor Xuanzong's behalf. It was further said that while previously, the common populace already had a custom of sacrificing joss paper to the spirits, it was Wang who brought this custom into official ceremonies.
During Emperor Suzong's and Emperor Daizong's reigns
After Emperor Xuanzong's son became emperor in 756, Wang Yu was promoted to be the minister of worship . Because his worship of the gods pleased Emperor Suzong, Emperor Suzong often gave him rewards. In 758, when Emperor Suzong removed the chancellors and from their posts, he made Wang ''Zhongshu Shilang'' -- the deputy head of the legislative bureau of government and gave him the designation ''Tong Zhongshu Menxia Pingzhangshi'' , making him a chancellor ''de facto''. It was said that even before this, Wang did not have a good reputation among the people, and after he was made chancellor, his reputation grew worse due to his incompetence.
At Wang's suggestion, Emperor Suzong built an altar dedicated to the god ''Taiyi'' to the south of Chang'an. Around this time, Emperor Suzong was ill, and the fortunetellers told him that he was being cursed by a god of a mountain or a river. Wang thus suggested that a group of witches and eunuchs be commissioned to go to various mountains and rivers of the empire to pray for Emperor Suzong. The witches that Wang selected used this opportunity to extort bribes from the local officials. One of them, who was sent to Huang Prefecture , took an entourage of several tens of young hoodlums with her and stayed at the station for imperial messengers with them. When the prefect of Huang Prefecture, Zuo Zhen , visited in the morning, he found the station door locked. He became angry, and he ordered that his police officers break into the station and that the witch be dragged out to be decapitated. He also killed the hoodlums that she was with, and then confiscated the bribes that they were carrying. He submitted the funds to Emperor Suzong and requested that the funds be used to pay the taxes that the people of Huang Prefecture would otherwise be responsible for. Emperor Suzong accepted the funds but did not punish Wang. In 759, indeed, pursuant to Wang's suggestions, he personally offered sacrifices to the gods of the nine palaces . Later that year, however, he made Wang the minister of justice and removed him from the chancellor position.
In 760, Wang was made the prefect of Pu Prefecture , as well as the military governor of the surrounding prefectures. In 761, Wang was made the secretary general at Yang Prefecture as well as the military governor of Huainan Circuit . After an occasion after Emperor Suzong offered sacrifices, he made Wang the governor of Yue Prefecture as well as the military governor of Zhedong Circuit . Sometime thereafter, he was recalled to serve as ''Taizi Shaobao'' and then ''Taizi Shaoshi'' -- both positions advisorial positions to the crown prince. Wang died in 768, during the reign of Emperor Suzong's son . He was buried with honors and given the posthumous name ''Jianhuai'' . His great-grandson Wang Tuan later served as a chancellor near the end of Tang Dynasty, under .