Mayor Bloomberg yesterday said his child-protective services chief was doing a heckuva job — just a day after two ex-Administration for Children’s Services workers were indicted in the September death of starved and beaten 4-year-old Brooklyn girl Marchella Brett-Pierce.

“I have 100 percent confidence in John Mattingly. This city is so lucky to have him,” gushed Bloomberg about the ACS boss. “I don’t know what you’d do if you lose him . . . This guy is world renowned.”

Two of Mattingly’s ex-subordinates, caseworker Damon Adams and supervisor Chereece Bell, were indicted Wednesday on charges of criminally negligent homicide related to their alleged failure to monitor Marchella.

Daniel Flanzig, a lawyer who is suing ACS over the horrific 2006 death of 7-year-old Nixzmary Brown, yesterday blasted Mattingly’s agency, saying, “Nobody is supervising the staff.”