Ferreira takes over at Panathinaikos
The 64-year-old Portuguese has signed a one-and-a-half-year contract which comes into effect on Sunday.
"Panathinaikos announces that the club has come to an agreement with Mr. Jesualdo Ferreira, " said Panathinaikos in a brief media statement.
Ferreira takes over from Nikos Nioplias, who parted company by mutual consent last Monday after coming under pressure over the team's defensive style of play.
Ferreira's first match in charge will be Wednesday's Champions League encounter against Barcelona in Athens.
Ferreira told reporters: "I'm very satisfied with my contract and our target now is to get down to hard work. The aim is for Panathinaikos to win the league."
Panathinaikos lead the Greek league but are bottom of Group D in the Champions League and need to beat Barca to keep alive their slim hopes of qualifying for the knockout stage.