Italy was in shock following the sudden death on Sunday of the 31-year-old defender who played for his country 14 times.
"Fiorentina and Davide's family inform you that the autopsy will be performed tomorrow... The funeral will take place on Thursday in the Santa Croce basilica," the Serie A club said Monday on its Twitter account.
A judicial inquiry had been launched following the death of the player, who was found dead in his hotel room in Udine, where his team was due to play Udinese on Sunday.
De Nicolo was quoted Sunday as saying Astori died of "natural causes" after a "cardiac circulatory collapse" -- a type of heart attack.
More From This Section
All seven matches in Italy's top flight on Sunday were postponed following the news of Astori's death.
Dario Nardella, the mayor of Florence, said the city would observe a day of mourning for the player's funeral.
Former national team coach Antonio Conte and World Cup winner Gianluigi Buffon paid emotional tributes to Astori, describing their Italian compatriot as "fantastic" and "a great guy".
"This is a tragedy and it really hurts me. It's very difficult at this moment to find the right words for the family," Conte told Sky Sports on Sunday ahead of his side's 1-0 loss to Manchester City.
Veteran Buffon, the Juventus captain, called Astori "a great man".
Buffon, who wrote in a post on Instagram accompanied by a photo of the two players exchanging pennants before a game between their clubs, said he did not usually make a habit of expressing his feelings about others.
Astori began his career at AC Milan, also playing for Cagliari and Roma before joining Fiorentina in 2015.
He made his international debut under coach Cesare Prandelli in March 2011 as a first-half substitute in a 2-0 victory over Ukraine in Kiev before getting sent off with 17 minutes remaining.