Barnsley have appointed Oldham manager Lee Johnson as their new head coach on a three-and-a-half-year contract.
The clubs have agreed an undisclosed compensation deal for the 33-year-old and his assistant Tommy Wright.
Johnson leaves Oldham ninth in League One, seven places higher than his new club, who he watched win 1-0 at Scunthorpe on Tuesday.
The Oakwell side have been without a manager since sacking Danny Wilson on 12 February.
Johnson told BBC Radio Sheffield: "I had two really positive conversations with the owner and I really felt the passion and belief he has.
"It wasn't a case of wanting to leave Oldham because I loved my time there, but I wanted to progress and give myself the best opportunity to achieve.
"It is a great time for me to come here and hopefully achieve something special."
Johnson became the Football League's youngest manager when he took over at Boundary Park in March 2013 aged 31, and guided the Latics to League One safety in his first season.
He helped them to a 15th-place finish last campaign and has an overall record of 36 wins, 35 losses and 32 draws from his time in charge.
|Youngest managers in English league football|
|Adam Murray (Mansfield), born 30 Sep 1981||Karl Robinson (MK Dons), born 13 Sep 1980|
|Alex Neil (Norwich), born 9 June 1981||Shaun Derry (Notts County), born 6 Dec 1977|
|Lee Johnson (Oldham), born 7 June 1981||Eddie Howe (Bournemouth), born 29 Nov 1977|
The Latics have placed first team coach Dean Holden, 35, in temporary charge for this Saturday's game against Preston.
Oldham chief executive Neil Joy said: "Whilst extremely disappointed that Lee has left the club, Oldham Athletic would like to thank him for the commitment and desire he has given to his role over the last two years and the contribution he has made to the development of the football club.
"We took a gamble in appointing the youngest manager in the Football League when he joined us and he has proved what we believed to be true at the time in that he is developing into one of the best young coaches in the country."
Barnsley, who have won their last two games under caretaker manager duo Mark Burton and Paul Heckingbottom, are 16th in League One, but just four points off the play-off places.
Johnson's first game in charge is Saturday's trip to Gillingham.