Brighton boss Graham Potter is delighted to secure Billy Gilmour from Chelsea.
The talented Scottish midfielder has seen his career stagnate in the past 18 months, after emerging onto the scene with the Blues a few years ago.
While a loan move was expected this summer, Gilmour has instead left Chelsea permanently for £10 million.
There is no buy-back clause in the agreement, but Chelsea have secured a sell-on arrangement for the 21-year-old.
"He will complement our existing midfield options," Potter said of new signing Gilmour.
"That experience at quite a young age shows the strength of character he has and we're really excited by his potential.
"Now it's about allowing him the time to get used to a new environment and settling in to our club. We can't wait to work with him."