He hailed from Juping 鉅平 (modern Tai'an 泰安, Shandong) and was a well-educated small official in his youth, before he was promoted to Grand master of remonstrance (jian dafu 諫大夫). Wang Zhang was known for his honest and straightforward speech. During the reign of Emperor Yuan's 漢元帝 (r. 49-33 BCE) he was promoted to Leader of the left section of the court gentlemen (zuocao zhonglangjiang 左曹中郎將) yet because he criticised the Director of the imperial secretariat (zhongshu ling 中書令) Shi Xian 石顯 he was slandered and dismissed.
Emperor Cheng 漢成帝 (r. 33-7 BCE) called him back to the court and promoted him to metropolitan commandant (sili xiaowei 司隸校尉), a position strong enough to resist the machinations of the empress' relatives. In 25 BCE Wang Zun was appointed metropolitan magistrate (jingzhao yin 京兆尹). At that time the most powerful person in the empire was General-in-chief (da jiangjun 大將軍) Wang Feng 王風, who had helped Wang Zhang to enter officialdom again. Wang Zhang nevertheless dared to criticize Wang Feng because of his unlimited power. Wang Feng took the chance when Wang Zhang recommended Feng Yewang 馮野王 for promotion and accused Wang Zhang of high treason. He died in prison.