Sannino was able to win just one of 12 Serie A games this season after replacing Corini, who left the club in May.
The last game of Sannino's tenure saw Chievo draw 0-0 against Milan at the Stadio Marcantonio Bentegodi, a result that saw the hosts' winless run extended to eight matches.
Corini will tasked with moving the club off the bottom of the table, having led them to a 12th-placed finish in Serie A last term.
In a statement, the club explained: "AC Chievo Verona announces that it has entrusted the conduct of the First Team to Eugenio Corini.
"The agreement is reached on a biennial basis (two-year deal)."
The first game of Corini's second stint in charge will see Chievo take on local rivals Verona on November 23.
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