Notts County have appointed Martin Allen as their new manager on a one-year rolling contract.
Allen, who becomes the club's eighth manager in 18 months, leaves League Two side Barnet where he was working on a non-contract basis.
Magpies chairman Ray Trew said: "Martin knows what it means to be successful at this level and has been brought in with both short-term and long-term aims."
The London club have said they may consider action against Notts County.
Barnet chairman Tony Kleanthous said: "Martin felt he could keep Notts County in League One and that would offer him the opportunity to challenge for Championship football next season.
"This is something I obviously could not match but I am disappointed by Notts County's behaviour in this regard, which is in contravention of football regulations, and we will seek advice as how best to deal with that."
Notts have lost their last seven games and slipped into the League One relegation zone, with a 3-1 defeat at Dagenham and Redbridge.
Chief scout Carl Heggs had been in charge of the last two games, following Paul Ince's departure at the start of the month.
"Having been at Dagenham on Saturday, it was clear that action had to be taken sooner rather than later to address our current situation," Trew added.
"I would like to thank Carl Heggs for stepping in at an incredibly difficult time and giving his all to the role of caretaker manager.
"But when the opportunity to sign Martin became available, we had to act quickly.
"I must reiterate that this is not a short-term fix. I see Martin as the man to make this position his own and to bring some much-needed stability back to the Notts County backroom team."
The former West Ham and QPR midfielder began his managerial career at Barnet, where he built a side that would go and reach the Conference play-off semi-finals.
By this time Allen had left for Brentford, where he twice reached the League One play-offs in a two-year spell at Griffin Park.
He then led MK Dons to the League Two play-offs but lost to Shrewsbury in the semi-finals.
In May 2007, Allen joined Championship side Leicester City but left after just four games in charge and, after a year out of the game, took over at Cheltenham in September 2008.
He was placed on gardening leave in October 2009 and left the club two months later.
Allen took over at League Two strugglers Barnet at the end of last month and oversaw a three-game unbeaten run.
The Magpies have also confirmed that assistant manager Alex Rae and first-team coach David Farrell have been relieved of their duties at Meadow Lane.