Neil Lennon won three league titles and two Scottish cups in his previous spell at Celtic
Neil Lennon says it's "an honor" to have been invited to manage Celtic for the second time after Brendan Rodgers has completed his move to Leicester City.
Lennon, 47, will assume the duties until the end of the season, starting with Wednesday's Premiership game against Hearts at Tynecastle.
The Northern Irishman returns to the club where he won three titles in 2011, after having Hibernian left last month.
"It's a club that already occupies a big place in my life," Lennon said.
Lennon, who will be assisted by current coach John Kennedy and former Irish international Damien Duff, also won two Scottish Cups for four years at Celtic Park.
Previously, the former midfielder had played seven games with the club in seven years before leaving in 2007.
"I've already given everything to Celtic as a player and manager in my career and I'm ready to do the same again," added Lennon, who will be shown at 10:00 GMT on Wednesday.
"I will do everything in my power to continue the great work done in recent years.I return to one of the biggest and best football clubs in the world and I look forward to to start."
"He knows what it means to be a Celtic manager"
Rodgers signed a contact with Leicester until June 2022 and succeeded Claude Puel, sacked Sunday after 16 months of management.
It is a return of Premier League for Rodgers, who has already led Liverpool and Swansea City.
Lennon, meanwhile, left Hibs in controversial circumstances in January, the Scottish part of the Premiership claiming that he had "not been fired" and "had not resigned".
He left Celtic in 2014, before an unfortunate passage with Bolton Wanderers in the English championship.
"By bringing Neil back to the end of the season, we have named a man who knows what it means to be a Celtic manager and who knows how to win," said Celtic general manager Peter Lawwell.
"We know that he has the commitment and the desire to meet the challenges ahead.
"We are excited to promote John Kennedy to the position of Deputy Director and to integrate Damien Duff into our first team management group, which will provide vital continuity and allow us to strengthen Brendan's legacy."
"An appointment stabilizes the ship" – analysis
Former Celtic striker Scott McDonald
It is very good, from the point of view of the Celts, to have been able to bring somebody so quickly to stabilize the ship. As a player, you always want to know and see your leader and that someone comes immediately. There are still players who have had Neil as a manager and I'm sure that they will send a message to other players about the type of manager he is.
What he knows about this football club, that's all, so I think for the moment, it's the perfect rendezvous. I can not imagine going in and changing too much. I think he's just going to follow what has been successful and his men's management skills are essential for the race at the end of the season.