This marks the return of Roberto De Zerbi, who previously coached Brighton, to England and the Premier League. His most recent coaching job was at Marseille in France.
Now he will try to keep the big club, which has Swedish stars Dejan Kulusevski and Lucas Bergvall, in the top division.
De Zerbi replaces Igor Tudor and becomes the team's third coach this season.
"Our first priority is to climb the Premier League table; that will be our sole focus until the final whistle of the last game of the season," De Zerbi said.
The big club is just above the relegation zone, one point ahead of their London counterpart West Ham, who are in the relegation zone.
