He’s putting his money where his mouthpieces are.

Mayor Zohran Mamdani’s new activist-packed outreach office that critics have blasted as a far-left propaganda organ is slated to cost taxpayers over $50 million — more than 10 times as originally promised, officials revealed Tuesday.

The Mayor’s Office of Mass Engagement is one of nine entirely new or revamped City Hall offices Mamdani has launched that’ll cost a combined at least $155 million and add dozens of new workers to the city payroll, a Post analysis found.

The office was previously expected to have a $5.1 million budget, but Mamdani’s budget director Sherif Soliman let slip during a City Council hearing that the overall cost would be $53 million, with $2.8 million earmarked for new staff.

Insiders have raised alarms about the mass engagement office for months, questioning what it’ll actually do beyond seemingly using taxpayer money to push the agenda of Mamdani’s Democratic Socialists of America activist base.

The office has mainly focused on getting New Yorkers out to testify at a Rent Guidelines Board about a rent freeze for rent-stabilized units — a key campaign promise from Mamdani — through using volunteer canvassing in city neighborhoods.

Critics argued the move could run afoul of conflict-of-interest laws by injecting political influence into government.

The council budget hearing Tuesday also raised questions about whether the office will effectively engage with groups that didn’t fall under the lefty umbrella.

City Councilwoman Lynn Shulman raised concerns about the new office absorbing the longstanding community affairs unit, which served to connect New Yorkers to City Hall.

She said past mayoral administrations assigned a point person for council and community boards to reach out to over issues, but that has yet to happen.

The concerns dovetailed with those from a Manhattan community board member.

“Only one staffer in this office is dedicated to liaising with all of Manhattan’s community boards, so where exactly is all this money going?” the board member, who did not want to be named, told The Post. “If it’s to support the mayor’s political priorities, that’s unacceptable.”

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The Post previously reported on the new office’s job listings that came with cushy six-figure salaries, with the mayor even tapping longtime DSA member and organizer Tascha Van Auken as commissioner of the outreach agency.

One mass engagement office staffer last week sparked a major political flap after telling Latino advocates the mayor was canceling an annual reception at Gracie Mansion typically held on the Thursday evening before the Puerto Rican Day parade.

A City Hall insider blamed the “junior staffer who spoke out of turn” for the blunder — and claimed that Mamdani always intended to host the Puerto Rican Heritage reception at the mayoral residence. 

The Post has since received an invite to the event, which will be held Friday afternoon, but it remained unclear if the offer smoothed over the outrage.

The office also organized a “Jewish Heritage” celebration at Gracie Mansion that many high-profile Jewish leaders boycotted over Mamdani’s fiery criticism of Israel.

“The mayor is just wasting taxpayer dollars to create jobs for his socialist army who otherwise is unemployable in the real world,” one anonymous Democratic operative said. 

Mamdani’s grab bag of new or revamped offices also includes his significantly watered-down $41 million Office of Community Safety tasked with reshaping how the city responds to 911 calls and an expanded Office to Protect Tenants and Hate Crime Prevention office.

Another Democratic operative blasted Mamdani for lavishing funds on the mass engagement office so shortly after crying poverty during state budget talks.

“Fifty‑three million dollars for what is basically the NYC Office of the Democratic Socialists of America … you can’t make this up!” the operative said.

“Months after begging the governor to plug his budget holes, Mamdani suddenly finds tens of millions for an in‑house propaganda shop to promote himself and muscle the Rent Guidelines Board, staffed by his closest socialist buddies. Voters are unlikely to look kindly on this type of brazen taxpayer‑funded self‑dealing.”

– Additional reporting by Matthew Fischetti