"The people have asked for new leadership in Cuyahoga County. The public should be assured we are moving in a new direction," he said, in a prepared statement.
Cuyahoga County Coroner Frank Miller, Engineer Robert Klaiber Jr., Adult Services Director Susan Axelrod and Children and Family Services Director Deborah Forkas are all being replaced.
FitzGerald did not name successors but said transition plans are in place for each of the departments that are affected.
Klaiber professed to be unaware of corrupt behavior by some of his employees.
Miller was embroiled in a controversy when he said he was pressured into hiring Pat Coyne, someone with ties to Bill Mason.
Forkas's office was in controversy last year dealing with placement of children.
FitzGerald also announced the layoffs of four members of the Service Employees International Union. FitzGerald asked county workers, including unions, to take furlough days to help balance the 2010 budget.
FitzGerald himself took days to set an example.
SEIU members voted not to take furlough days. The four workers laid off will save the county the equivalent of all members taking furlough days.
"During these tough economic times, we must make decisions based in the spirit of shared sacrifice," FitzGerald said.