Ben Gibson has joined Burnley on a four-year deal from Middlesbrough for a joint club record fee.
The 25-year-old moves to the Clarets for £15m, matching the fee paid for Chris Wood last summer, and becomes the club's first signing of the summer transfer window.
Gibson underwent a medical on Saturday and returns to the Premier League after being an ever-present during his first experience of England's top flight during the 2016-17 season.
"I'm absolutely delighted. It's a big step for me. I've played for Middlesbrough for 15 years since I was a boy so it's a huge step and one I'm really, really excited about," Gibson told the club's official website.
"The measure of a fantastic team is not to do something once, but to repeat that time and time again.
"I know that's what Sir Alex Ferguson said about Manchester United. Sean Dyche and the team and everyone here did such a fantastic job last year in finishing seventh and qualifying for the Europa League.
"Let's hope this is a real, real good chapter in Burnley's history and this is just the start of things to come."