Ong Sung-woo finished at fifth place in the second season of Mnet’s Produce 101 and became a member of its derivative boy group Wanna One. They debuted in August 2017 with the extended play 1×1=1 (To Be One). In November of that year, they released the mini album’s repackaged version called 1-1=0 (Nothing Without You). The combined sales of their first two albums topped one million. In October 2018, the group released their first studio album called 1¹¹=1 (Power of Destiny).

Ong Sung-woo made his acting debut as the lead actor in JTBC’s A Moment at Eighteen, which won him the Rookie of the Year trophy at the 4th Asia Artist Awards and Best New Actor at the 12th Korea Drama Awards. He also earned a Best New Actor for TV nomination at the 56th Baeksang Arts Awards for his work in the series. In March 2020, he released his first extended play as a solo artist titled Layers. Also in 2020, he headlined the JTBC romantic comedy More Than Friends, opposite Shin Ye-eun.

Ong Sung-woo has an older sister. He graduated from Dong Seoul University’s Department of Acting Arts. He enlisted for his mandatory military service in April 2023.