Yao Hong was born in 388, during the reign of his grandfather Yao Chang (Emperor Wuzhao), two years after Yao Chang took Chang'an as his capital and created Yao Hong's father Yao Xing as his crown prince. He was Yao Xing's oldest son. The first historical reference to Yao Hong was in 402, when Yao Xing, who became emperor in 394, created him crown prince, after much hesitation, as Yao Hong was described as loving and kind, but weak in his personality and often ill. Yao Hong was also described as favoring arts and literature. Later in 402, when Yao Xing battled Emperor Daowu of Northern Wei, Yao Hong was in charge at the capital. In 407, Yao Xing transferred some imperial authorities to him. In 409, when Yao Xing was battling the rebel general Liu Bobo, who had established Xia, Yao Hong was again in charge of the capital when Liu Jue () rebelled, and Yao Hong defeated his rebellion. When his subordinates suggested that the victory be commemorated on an open bulletin, written on cloth, Yao Hong declined, reasoning that it was his responsibility to make sure that no rebellion occurred, and that such a victory over a rebel was nothing to be proud of.