Napoli relayed a welcome video on Twitter which saw Ancelotti make a multilingual introduction:
Sky Sports News reported Ancelotti has penned a three-year deal at the Stadio San Paolo:
The 58-year-old has been out of work since being sacked by Bayern Munich last September.
He was heavily linked with the Italian national-team job before the Italian Football Federation confirmed Roberto Mancini in the role, per Tom Doyle of the Evening Standard.
Ancelotti is one of the most decorated managers still working. He is one of only two men to win the UEFA Champions League or European Cup three times as a manager—the other is Bob Paisley.
Meanwhile, he has won league titles in Italy, France, England and Germany.
In three seasons under Sarri, Napoli finished second twice and third once in Serie A.
De Laurentiis is doubtless hoping Ancelotti can push Napoli to greater heights as they attempt to break Juventus' seven-year monopoly of the Serie A title.