Palermo was officially relegated after former player Luca Toni scored to hand Fiorentina a 1-0 win in Serie A on Sunday.
The result left the Sicilian side five points behind 17th-placed Genoa, which drew 0-0 at home to Inter Milan. With one round remaining, Torino also secured safety with a 1-1 draw at Chievo Verona. It is six points above Palermo.
Genoa's result meant Siena was also relegated, without kicking a ball. It later lost 2-1 at second-place Napoli. Palermo and Siena join already relegated Pescara in Serie B next season.
Fiorentina moved provisionally one point behind AC Milan in the race for third spot and entry into the Champions League qualifying round. Milan hosts Roma in the evening game.
Toni scored 30 league goals in his first season at Palermo, to fire them into the top flight in 2004 for the first time in 31 years. The Italian striker then helped the side qualify for Europe before departing for his first spell at Fiorentina.
He scored four minutes from halftime. Borja Valero sent Juan Cuadrado down the right flank and his cross to the far post allowed Toni to slot home from close range. Fabrizio Miccoli's free kick flew inches wide of the post for Palermo in the final minutes.
Siena had been fighting against relegation since a six-point penalty for its part in the betting scandal was imposed at the beginning of the season. It was playing for little more than pride against Napoli and took the lead through Fabrizio Grillo, on his Serie A debut.
Edinson Cavani, who had hit the woodwork twice and had a goal ruled out for offside, leveled before Marek Hamsik won the match for Napoli in stoppage time
