Kim Woo-seok debuted in 2015 with Up10tion with the extended play Top Secret. In 2019, he joined as a contestant in Mnet’s survival reality show Produce X 101, where he finished second. This earned him a spot in the 11-member boy group X1. They disbanded shortly in January 2020 as a result of the Mnet voting manipulation scandal. In May 2020, Kim Woo-seok debuted as a soloist with the extended play 1st Desire (Greed). This was followed by his acting debut in the romance youth web series Twenty-Twenty. In 2021, he appeared as one of the main characters of the tvN fantasy drama Bulgasal: Immortal Souls. In 2023, he was cast opposite Kim Bora in Cinema Heaven’s slice-of-life series Finland Papa.

Kim Woo-seok enrolled at Dong-ah Institute of Media and Arts but later transferred to Global Cyber University.