Warnock has signed a contract that will keep him in charge of the Whites until the end of the 2012/13 season.
Warnock was sacked by Queens Park Rangers in January.
Chairman Ken Bates told the club’s official website: “We believe the appointment is arguably the most important we have made.
“The objective was to appoint a manager who had a proven track record of getting teams promoted and in Neil we have a man whose record is second to none.
“We want to be in the Premier League and we will support him in the quest to get us there.”
Warnock said: “I feel I have one big challenge left in me and believe Leeds is a club that should be in the Premier League.
“I want to be the man who is able to deliver this for a set of fans who never cease to amaze me with their numbers and their loyalty.
“Having met with Ken Bates, it was an easy decision to take up the challenge and with his support, we share the same vision of getting Leeds United in the Premier League.”
