A new deal was signed by Chelsea youngster before loan move Albion for the 2020/21 season on loan.
The highly-rated youngster signed a new five-year contract before completing the transfer, which will appear to keep him at his boyhood club until at least 2025.
His loan transfer is his first to a top-flight club, having spent the first half last season with Charlton before transferring to Swansea City.
After completing the transfer, the 21-year-old spoke;
“There was a lot of interest from the Premier League, which is where I wanted to play this season, but this is where I want to be,” he said.
“West Brom stood out to me because of the way they played last season. I played against them two or three times and I liked how they approached the game.
“I felt that it would suit me and it would be best for my development. I felt it could help me become the player I want to be and I’m pleased to get this agreement sorted.”