Mayor de Blasio brought down the hammer Thursday on three charter schools operated by his nemesis Eva Moskowitz, leaving hundreds of kids without classrooms this fall.

“This has to be the saddest day for the Success Academy’s children, family, teachers, school leaders,” Moskowitz said after meeting with stunned charter parents in Harlem.

“Right now, our kids are being evicted. Evicted out of their school. It’s wrong and we need an explanation. You’re going to have to ask Mayor de Blasio what the motivations are for a decision that will hurt so many children now and, frankly, forever.”

Fulfilling a campaign pledge to limit charter expansions within public-school buildings, de Blasio revoked approvals granted last year by the Bloomberg administration to two new Success Academy schools and to a third that planned to expand.

At the mayor’s behest, the Department of Education conducted a review of 45 “co-locations” in which multiple schools share a single building — including 19 charters.

It revoked nine of the arrangements covering six public schools and the three charters, which all carried Moskowitz’s Success Academy banner.

Left to fend for themselves were:

• A planned elementary charter that was going to open within the August Martin HS complex in Jamaica, Queens, with 200 kindergartners and first-graders starting in September.

• A K-4 charter slated for Murry Bergtraum HS near City Hall.

• New fifth and sixth grade students hoping to attend Success Academy IV middle school classes at the PS 149/Sojourner Truth building on West 118the Street, which was put off limits.

Moskowitz called on Gov. Cuomo and the Legislature to undo the actions. “We need political leadership,” she said.

“We need someone who will put kids ahead of politics. We are a public school. Public schools do not pay rent.”

She vowed to sue the mayor to win back the lost space.

Schools Chancellor Carmen Fariña’s office also told a fourth charter school, American Dream Charter in the South Bronx, that it would be getting less space inside PS 30, reducing its capacity by 25 to 33 percent.

Charter advocates were livid.

New York Charter School Center CEO James Merriman blasted de Blasio’s team for acting without consulting the parents involved.

“It is hard to believe that an administration that constantly urges stakeholder engagement did not hold one meeting with affected families before making these recommendations,” he said.

The chancellor’s office provided alternative sites — what it called “better matches” for three of the six affected traditional public schools.

After bumping the Success Academy elementary charter from the Murry Bergtraum site, the administration set aside the space for two new high schools.

“We do not believe new elementary schools should be opened on high-school campuses,” said Department of Education spokesman Devon Puglia.

While the rug was pulled out from under three Success Academy schools, education officials emphasized that five others were approved.

De Blasio insisted the rollbacks were done fairly and were not a vendetta against Moskowitz, whom he has singled out in the past as getting special treatment.

“There’s no way in hell Eva Moskowitz should get free rent, OK?” de Blasio said last June during the mayoral race.

The mayor pointed out that he could have come down harder than he did.

“Some of her schools were approved and others were not,” he said.

Additional reporting by Yoav Gonen, Kevin Fasick and Beth DeFalco