Chelsea have acted quickly in finding a replacement for Roberto di Matteo as the club's new manager.
Benitez will take charge of a Chelsea club that lost 3-0 to Juventus on Tuesday in the Champions League, and they do not control their own destiny to make the knockout round at the moment.
In domestic play, the Blues have gone on a four-match winless streak, which includes losses to West Brom and Manchester United along with disappointing draws against Swansea and Liverpool, and have dropped from first to third in the EPL table.
The first match in charge for Benitez will be Sunday's massive EPL clash with second-place Manchester City at Stamford Bridge.
The 52-year-old Spaniard becomes the ninth manager to run the club since owner Roman Abramovich took over the club in 2003.
Benitez does have an impressive resume from his early managing career with two La Liga titles and a UEFA Cup won in his three years at Valencia, as well as a Champions League title in the 2004-05 season with Liverpool.
His most recent job came back in 2010, when he disappointed with Inter Milan and only lasted six months at the San Siro.
Benitez's main goal at Chelsea will be to win the Premier League title as the Champions League looks out of reach unless they win on the final group stage match day and Juventus lose to Shakhtar Donetsk.
One thing is for sure, Benitez will be under immense pressure to succeed at Chelsea.