Napoli replaces Walter Mazzarri.
Benitez guided Chelsea to victory in the Europa League and a third-place finish in the 2012/2013 English Premier League to ensure Champions League football at Stamford Bridge next season.
Napoli president, Aurelio De Laurentiis, on Monday evening tweeted a picture of himself shaking hands with Benitez on his verified Twitter account, and wrote, “Rafa Benitez is the new coach of Napoli. A great man with international experience. A leader”.
The Spaniard won the Champions League with Liverpool in 2005 and this month’s Europa League triumph was his second win in the competition after he won it with Valencia in 2004 before moving to Anfield.