He returns for a second spell in charge as manager.
Warnock has been appointed on a two-year deal, taking charge with immediate effect. He takes over a side without a win from their opening two Premier League games, but they did progress to the third round of the League Cup after a 3-0 win over Walsall.
His first game in charge will be against Newcastle United at St James' Park on Saturday afternoon.
Former West Bromwich Albion head coach, and former Liverpool and Chelsea assistant manager Steve Clarke was also said to be in the running for the post. Malky Mackay was reportedly set to be offered the role last week but that didn't materialise because of reasons which are well-documented.
Some will see the appointment of Warnock as an odd move. In 1991/92 he was relegated from the top flight with Notts County, in 2006/07 he was in charge of Sheffield United but were relegated on the final day after a 2-1 loss to Wigan Athletic, and was sacked midway through the 2011/12 season when in charge of Queens Park Rangers in 17th position.
Warnock spent three years in charge at Selhurst Park between 2007 and 2010 before taking up the job at QPR. During his first spell at the Eagles. He left the club when it went into administration.