Chelsea have sold Billy Gilmour to Brighton for £10m.
The 21-year-old, who has 15 caps for Scotland, has signed a four-year deal with his new club.
Gilmour could make his debut this weekend against Leicester City.
After moving to England from Rangers as a teenager in 2017, Gilmour made his Premier League debut as an 18-year-old in August 2019.
He spent last season on loan at Norwich City, where he made 21 starts.