He originally belonged to Gongsun Zan. When Gongsun Zan sent Liu Bei to resist Yuan Shao on behalf of Tian Kai, Zhao Yun went along with Liu Bei and took charge of his cavalry. Records, Shu 6 §39
When Cao Cao led his elite cavalry in hot pursuit and caught up at Changban in Dangyang, Liu Bei abandoned his wife and children and fled south with Zhuge Liang, Zhang Fei, Zhao Yun and some dozens of horsemen. At that time Zhao Yun personally carried the infant son, that is, the Later Sovereign, Liu Shan, and protected the Later Sovereign's mother, Lady Gan, so that both escaped harm. The Biography of Empress Gan likewise records that in the desperate situation Liu Bei abandoned Lady Gan and the Later Sovereign, but that they escaped the disaster thanks to Zhao Yun's protection. Zhao Yun was promoted to General of the Standard (Yamen jiangjun). Records, Shu 2 §22Records, Shu 6 §39Records, Shu 4 §3
When Liu Bei entered Shu, Zhao Yun stayed behind in Jing Province. When Liu Bei turned back from Jiameng to attack Liu Zhang and summoned Zhuge Liang, Zhuge Liang led Zhao Yun, Zhang Fei and others up the Yangtze, pacifying the commanderies and counties along the way. At Jiangzhou, Zhao Yun went separately up the Outer River to Jiangyang and joined Zhuge Liang at Chengdu. After Chengdu was pacified he became General Who Assists the Army. Records, Shu 6 §39–40Records, Shu 2 §32
In the 1st year of Jianxing (223) he became Central Protector of the Army (Zhong hujun) and General Who Conquers the South, was enfeoffed as Marquis of Yongchang Village, and was then transferred to General Who Guards the East (Zhendong jiangjun). In the 5th year of Jianxing (227) he followed Zhuge Liang to garrison Hanzhong. Records, Shu 6 §40–41
The following year Zhuge Liang spread word that he would take Mei County by way of the Xie Valley road, and had Zhao Yun and Deng Zhi occupy Ji Valley as a decoy force. While Cao Zhen of Wei sent a great army to block them, Zhuge Liang personally attacked Qishan. With weak troops against a strong enemy, Zhao Yun and Deng Zhi fared badly at Ji Valley, but they gathered their men and held firm, and did not suffer a great defeat. When the army withdrew, Zhao Yun was demoted to General Who Guards the Army. In a memorial Zhuge Liang cited "the failure to take precautions at Ji Valley" together with the disobedience of orders at Jieting, and said the fault lay entirely with himself, for he had no proper method in assigning men. Records, Shu 5 §32–33Records, Shu 6 §41
He died in the 7th year of Jianxing (229). Originally, under Liu Bei only Fa Zheng had received a posthumous title, and under the Later Sovereign posthumous titles went to Zhuge Liang, Jiang Wan and Fei Yi, to the favored Chen Zhi, and to Xiahou Ba, who had come from afar to submit. Posthumous titles were then conferred on Guan Yu, Zhang Fei, Ma Chao, Pang Tong and Huang Zhong, and on Zhao Yun as well, whose title was Marquis Shunping; opinion at the time regarded this as an honor. According to the Biography of the Later Sovereign, Guan Yu and the other four received their titles in the ninth month of the 3rd year of Jingyao (260), and Zhao Yun in the third month of the 4th year of Jingyao (261). Records, Shu 6 §41Records, Shu 3 §38 · 40–41
His eldest son Zhao Tong succeeded him, rose to Gentleman of the Tiger Guard (Huben zhonglang), and acted as supervisor of the army (lingjun). His second son Zhao Guang, a Standard General, followed Jiang Wei to Tazhong and was killed in battle. Records, Shu 6 §42
The Encomia on the Supporting Ministers of Ji Han, written by Yang Xi in the 4th year of Yanxi (241), praised Zhao Yun, General Who Conquers the South, as "generous and weighty." Beneath this encomium Chen Shou noted that Chen Dao, who has no biography of his own, was always second only to Zhao Yun in reputation and rank, and that both were renowned for loyalty and courage. Records, Shu 15 §33 · 58
In his assessment Chen Shou said that Huang Zhong and Zhao Yun were strong, fierce, vigorous and brave, and together served as claws and teeth, and that they were perhaps of the same kind as Guan Ying and the Lord of Teng. Records, Shu 6 §44