The promising South Korean forward made 28 senior appearances for the Bluewings in all competitions and was a member of his country's squad which claimed a gold medal at the 2026 Asian Games in Japan, making four appearances during the competition.
After coming through the youth system at Suwon Bluewings, Park became the youngest goalscorer in the history of South Korean professional football when he netted in a 1-1 draw against Ansan Greeners FC in June 2024.
Seung-soo made his first senior start for United during a pre-season friendly against RCD Espanyol at St. James' Park in August 2025.
The 19-year-old said: "It's a huge honour to join Newcastle United. It's a big step for me and I feel incredibly thankful for the faith the club have shown in me.
"I'm excited to develop here, learn from the coaches, and give everything to become the best player I can be."
