Chris Wilder has left Oxford United to become the new manager of Sky Bet League 2 basement side Northampton Town on a three-and-a-half-year contract.
The Cobblers had been searching for a replacement for Aidy Boothroyd since just before Christmas.
The club were given permission to speak to Wilder over the weekend and agreed compensation terms with Oxford.
Wilder, who led United back to the Football League during his five years in charge, resigned on Sunday afternoon and officially took the reins at Sixfields on Monday morning. His first game in charge will be Tuesday night's home clash with Rochdale.
"I am delighted to be able to appoint Chris," Northampton chairman David Cardoza told the club's official website.
"I know it has been a frustrating time for our supporters and I apologise for that but I make no apologies for taking our time and making sure we made the right appointment.
"We were in the capable hands of Andy King so we took our time, assessed our options, spoke to a lot of people in the game and all the reports we got on Chris were excellent.
"We were looking for a manager who has the experience required to guide us out of our current position and one who is ambitious and driven enough to take the club forward in the medium term, and Chris is the perfect choice."
Wilder's assistant will be Alan Knill, who was sacked by Torquay at the start of January.