| King Soseong 소성왕 昭聖王 | |
| Succession: | King of Silla |
| Reign: | 798-800 |
| Predecessor: | Wonseong of Silla |
| Successor: | Aejang of Silla |
| Father: | Prince Hyechung |
| Mother: | Queen Seongmok |
| Birth Date: | ??? |
| Death Date: | 800 |
| Death Place: | Silla |
| House: | House of Kim |
| Hangul: | 소성왕 |
| Hanja: | 昭聖王 |
| Rr: | Soseong Wang |
| Mr: | Sosŏng Wang |
| Hangulborn: | 김준옹 |
| Hanjaborn: | 金俊邕 |
| Rrborn: | Gim Jun-ong |
| Mrborn: | Kim Chunong |
Soseong of Silla (died 800) (r. 798–800) was the 39th to rule the Korean kingdom of Silla. He was the grandson of King Wonseong, his father Kim In-gyeom having died before he could take the throne. He married Lady Gyehwa, the daughter of the daeachan Suk-myeong.
Soseong died only nineteen months after taking the throne. On his deathbed, King Soseong, he called his younger brothers, including Eonseung, and told them that he would hand over the throne to his son as his grandfather had wished, and that they should respect the succession. However, this was ignored as Aejang was usurped, which brought on a renewal of the succession strife which typified later Unified Silla.[1]
Soseong of Silla, who was raised in the royal court before he ascended the throne, was given a royal rite in 789, and went to the Tang dynasty in 790. He was appointed to the Si-jung in October 791, but retired due to illness in August the following year. When Uncle Uiyoung died early in 794, he was proclaimed Crown Prince in the year 795.[2]