Prior to that, he served as a Sangdaedeung to King Hyegong of Silla.
He married Lady Gujok, the daughter of gakgan Kim Yang-pum.
Seondeok served under King Hyegong in the position of sangdaedeung.
In 780, ichan Kim ji-Jeong, led a rebellion against King Hyegong.
However, the rebel forces succeeded in storming the palace and killed King Hyegong and his Queen.