Kristoffer Ajer has completed his move to Brentford from Celtic.
The Bees are paying a fee in the region of £13.5m for the 23-year-old Norway centre-back, who has signed a five-year contract.
Bees boss Thomas Frank told the club website: “We wanted to get another central defender in, and Kris was our first choice. We think he fits the position specific profile perfectly, especially on the ball.
“Kris is very composed and can find the right passes between the lines. His level when bringing the ball forward is very high.
“As a defender he has the physicality that you need, and he won his duels when he played in the Scottish league. He can help us in both boxes, with his strength in the air.
“He is a player at a good age, and we think he come straight in and be ready to perform in the Premier League. But he also fits the way we want to recruit players and work with them.
“He can develop as a player and both Brentford FC and Kris can move to a higher level in the coming years.”