The 54-year-old coach has been released by Casteddu following their disappointing 3-2 home loss to Genoa last Sunday. He becomes the second manager to be let go on Tuesday, with Eusebio Di Francesco sacked by Hellas Verona earlier in the day.
“The club wish to thank him for his tireless and professional approach, and wish him all the best for the rest of his career.”
Semplici managed a total of 18 Serie A games for Cagliari, winning six, drawing five, and losing seven.
Former Torino boss, Walter Mazzarri, has been linked with the vacant position, as has Casteddu legend Diego Lopez.