Sunday’s Premier League game with Manchester City will be Walter Mazzarri’s last in charge of Watford.
The Italian was only appointed at Vicarage Road a year ago.
Mazzarri guided Watford to safety, but they have lost each of their last five games.
Chairman Scott Duxbury says the decision was made after a meeting about “the club’s future goals and aspirations”.
Mazzarri was Watford’s eighth manager in the last 6-years.