Fu Xun was from Niyang County (泥陽縣), Beidi Commandery (北地郡), which is around present-day Yaozhou District, Tongchuan, Shaanxi. He was well-read and known for giving critical commentary on people. He was recruited into the civil service and served as a Gentleman of Writing (尚書郎). He later moved to Jing Province (covering present-day Hubei and Hunan) and became a guest official under the provincial governor, Liu Biao.
In 208, shortly after Liu Biao's death, the warlord Cao Cao invaded Jing Province and his army arrived outside the provincial capital, Xiangyang. Fu Xun, who was then an Assistant Officer in the East Bureau (東曹掾), along with Kuai Yue and Han Song (韓嵩), urged Liu Biao's younger son and successor Liu Cong to yield to Cao Cao. Liu Cong heeded their advice. Fu Xun came to serve Cao Cao and received a title of a Secondary Marquis (關內侯) for his effort in persuading Liu Cong to surrender.
In 220, Cao Cao's son and heir Cao Pi forced the Han dynasty's last ruler Emperor Xian to abdicate the throne to him, and subsequently established the state of Wei, marking the start of the Three Kingdoms period. Fu Xun served as a Palace Attendant (侍中) and Master of Writing (尚書) in Cao Pi's imperial court. He died in the Taihe era (227-233) of the reign of Cao Pi's successor Cao Rui.
When Fu Xun was in Jing Province, he once commented that Pang Tong was a "half-hero", and foresaw that Pei Qian (裴潛) would become famous for his good moral conduct. Fu Xun's comment on Pang Tong proved accurate as the latter received lesser treatment as compared to Zhuge Liang when he came to serve Liu Bei. As for Pei Qian, he eventually became Prefect of the Masters of Writing (尚書令) in Wei and enjoyed a reputation for being virtuous. When Fu Xun was serving under Cao Cao, he accurately predicted that Wei Feng would start a rebellion one day, and this came true in 219.