Leeds United have appointed Paul Heckingbottom as their new manager on an 18-month contract, the club have announced.
The 40-year-old leaves Barnsley to move to Elland Road and has signed a contract that runs until the end of next season.
He succeeds Thomas Christiansen, who was sacked on Sunday after a dismal run of form which has seen Leeds not win a match since Boxing Day.
Leeds have fallen to 10th in the Championship and Heckingbottom leaves a side who sit 21st in the same division.
Heckingbottom only signed a new contract with Barnsley last week, when he said "there was never any doubt" he would commit to the club.
The coach was targeted by Leeds once Christiansen left, however, and the opportunity proved irresistible.
"It's a big opportunity at a big football club and it's something that you work hard for," he said.
"What appealed was the size of the club. When I spoke to Victor [Orta, director of football] and the owners they were aligned with what I was thinking and how I liked to work.
"I'm presuming that's the reason they thought I was right for the job as well, because I'm aligned with how they like to work, so hopefully that will be good for us going forward."
Barnsley said several members of their staff, including first-team coach Jamie Clapham, would join Heckingbottom at Leeds.
A statement from Barnsley said the club felt "thoroughly disappointed" by Heckingbottom's exit and "shocked" that he should want to leave.
"Yes, it was unexpected," Barnsley chief executive Gauthier Ganaye said in a statement on the club's website. "Yes, it has come during an already complicated period. Yes, it will make things more difficult short term, but our club is full of resources and it is certainly not dependent on one man alone."
Heckingbottom's first game as Leeds United boss will be the Yorkshire derby against Sheffield United at Bramall Lane on Saturday.