Nigel Pearson said it was an honour to be named the new Derby manager and he believes he is taking charge of one of the biggest clubs in the country.
Pearson, who was recently interviewed for the vacant managerial post at Aston Villa, ended his almost year-long absence from the game on Friday afternoon by signing a three-year contract at the iPro Stadium.
The 52-year-old was sacked by Leicester last June despite engineering a remarkable escape from relegation to the Sky Bet Championship, having won two promotions with the Foxes.
Pearson is the permanent successor to Paul Clement following his sacking in February and he and his assistant - former Derby defender Chris Powell - are tasked with steering the Rams back to the Barclays Premier League.
''I am honoured to be named as the manager of Derby County, which is one of the biggest clubs in the country, a club in excellent shape and one with strong ambitions. It is firmly focused on achieving Premier League football,'' Pearson told the club's official website, dcfc.co.uk.
''I will give absolutely everything I have to this role and do all I can to bring exciting, entertaining and winning football which our supporters can be proud of.''
Pearson was a contender for the Villa job and was the preferred candidate of chairman Steve Hollis, before Chinese businessman Tony Xia's proposed takeover changed the landscape.
It is understood Pearson only held talks with Derby this week but he quickly became the frontrunner.
His reputation has remained high as Leicester won the Premier League title with the majority of his old squad, under his successor Claudio Ranieri.
Pearson also won the League One and Championship titles during his time with the Foxes and it is his proven track record which Derby found so appealing.
President and chief executive Sam Rush said: ''As we expected, there was huge interest in the managerial position and we interviewed a number of high-calibre candidates during a very comprehensive and competitive process.
''We have chosen the outstanding person in Nigel, who has vast experience, a track record of success and a tangible desire to get this club into the Premier League.
"Nigel is a highly sought after, talented manager and I know he will give us absolutely everything to make this club successful. I am excited with what the future holds.
''I know our supporters will welcome him to the club and they will also be thrilled to see Chris Powell returning to us and further strengthening our coaching team.''
Having guided Derby to a top-six finish after his promotion from academy director to head coach following Clement's departure, Darren Wassall was also interviewed for the position but he will now return to his role with the youngsters. The Rams lost 3-2 on aggregate to Hull in the semi-finals of the play-offs.