Verona, who lost 4-0 at Cagliari on Saturday, have won only two games in the league as they sit four points below the safety zone.
"Hellas Verona FC announces that Paolo Zanetti has been relieved of his duties as head coach of the first team," the club said in a statement, adding that U-19 coach Paolo Sammarco would lead the first team's training session on Monday.
Zanetti led Verona to a 14th-place finish in the Serie A last season, avoiding relegation by six points. This season, they have fared worse, allowing a league-high 41 goals in 23 matches so far.
Verona host 19th-placed Pisa, with both teams on 14 points, in their next game on Friday.