Mayor de Blasio will headline a political fundraiser in Iowa without knowing who’s paying up to $2,000 to see him speak or where the cash will go – despite promising to stay away from “dark money.”

“We know there’s a lot that happens in the public process where there’s no disclosure of who the donors are – I don’t go near anything unless there’s full disclosure,” de Blasio said in February 2016.

Yet the mayor will speak at Progress Iowa’s fifth annual holiday fundraiser on Dec. 19 even though the group doesn’t disclose donors or spending. Tickets range from $30 to $2,000 for VIPs and at least 150 are expected.

Progress Iowa won’t have to reveal who’s paying to party with de Blasio or any of its other donors because it’s registered as a shadowy 501-c(4) non-profit.

The group only had to divulge basic information in its latest tax filing, showing $192,570 made and $216,454 spent last year.

While executive director Matt Sinovic said the group will cover about $500 in travel expenses for de Blasio, including airfare and a hotel stay, he refused to voluntarily disclose contributions and expenditures. Sinovic didn’t respond to a request for further comment.

Hizzoner’s appearance at the secretive group’s holiday shindig makes him look like a ho-ho-hypocrite, his critics said.

“It’s vintage de Blasio – saying one thing and acting a totally different way,” said Sal Albanese, a Democrat who ran unsuccessfully against de Blasio this fall.

Staten Island Assemblywoman Nicole Malliotakis, de Blasio’s Republican opponent, said of the Iowa fundraiser: “He needs to be pressed on whether people who do business with New York City are going to this party.”

Progress Iowa’s non-disclosure policy contradicts de Blasio’s own self-imposed rules. The 501-c(4) organization he created to promote his agenda, the now-defunct Campaign for One New York, released records twice a year detailing $4.4 million in donations since 2014.

“What we’ve said from the beginning is anything that’s supporting this administration’s goals or anything I’m involved in must be fully disclosed,” de Blasio said on Feb. 22, 2016, when asked about his group.

Those disclosures show money given to the Campaign for One New York were largely six-figure donations from unions and firms with business before the city. A sprawling federal probe into whether de Blasio or his aides had given favors in exchange for donations to the group and his 2013 campaign ultimately ended with no charges earlier this year.

City taxpayers will foot the bill for the mayor’s aide and NYPD detail during his jaunt to Iowa, a presidential-candidate proving ground where de Blasio already embarrassed himself trying to be a relevant national figure during the 2016 race.

The mayor’s office claimed de Blasio didn’t actually promise to avoid organizations that don’t divulge their donors, only that groups he controls would disclose them.

“It’s $50 holiday party that’s open to the public and attended by progressive Iowan activists,” de Blasio spokesman Eric Phillips said. “We’ll let you know if the Koch brothers show up.”