Maurizio Sarri left Lazio on Wednesday after coming to an agreement to terminate his contract ahead of his expected switch to Atalanta.
"S.S. Lazio announces that a mutual agreement has been reached to terminate the contracts of Head Coach Maurizio Sarri and his coaching staff," said Lazio in a statement.
Sarri, 67, leaves Lazio for the second time in just over two years after a disastrous season in which the Rome-based club finished ninth and lost in the Italian Cup final.
The campaign has been marked by a mass boycott of matches by supporters who want long-time owner Claudio Lotito to sell the club.
They have been crowned Italian champions twice, but the last time they won the Serie A title dates back to 2000.
Gennaro Gattuso is reported to be the favourite to replace Sarri at Lazio, his first job since stepping down as Italy coach following the Azzurri's failure to qualify for the World Cup.
Sarri is widely reported to be heading to Atalanta who are yet to dismiss their current coach Raffaele Palladino.