Jia Xu originally served as a commander under Dong Zhuo's general Li Jue, and he fought at the Battle of Hulao Gate in 190 AD. However, after the death of Dong Zhuo in 192, he served Li Jue independently, and he later joined Zhang Xiu after Li Jue mistreated him. Jia Xu was a brilliant strategist, and he suggested the ambush of Cao Cao at the 197 AD Battle of Wan Castle that slew his bodyguard Dian Wei and nearly Cao Cao. Cao Cao later returned to the castle and captured it despite Liu Biao's intervention, and Jia Xu was forced to surrender. He became one of Cao Cao's officers, but was held on a tight leash due to his fault for Dian Wei's death.
Jia Xu fought in the 211 AD Battle of Tong Gate, and Jia Xu assisted in the defeat of the army of Ma Chao, a Liang Province general who was fighting to avenge the death of his father Ma Teng. Jia Xu masterminded the destruction of Ma Chao's army, and was promoted. He died in 223 AD, shortly after the defeat at the Battle of Dongkou by Eastern Wu.