The 51-year-old has signed a two-year deal with club just 24 hours after Andrea Stramaccioni was relieved of his duties
The 51-year-old succeeds Andrea Stramaccioni, who was sacked on Friday.
"FC Internazionale would like to announce that the club has appointed Walter Mazzarri as the new head coach," read a statement on the club's official club website. "FC Internazionale would like to thank Andrea Stramaccioni for the great commitment and professionalism he showed in a particularly difficult year. Walter Mazzarri has signed a two-year deal."
Former Sampdoria boss Mazzarri had been heavily linked with a move to San Siro after guiding the Partenopei to an impressive second-place finish in Serie A this season, ending his four-year reign in Sicily with the club’s highest league finish in over twenty years and sealing qualification for next season's Champions League.
Inter will not compete in European competition next season after a disappointing campaign saw it end the season in ninth.