A teachers union staffer based in a Bronx elementary school was busted Thursday night for soliciting sex from an undercover NYPD cop posing online as a 14-year-old boy, officials said.

Jason Seto, 41, of Astoria, who worked out of PS 48 as a liaison with non-profit organizations, was collared while going to meet his target at a Five Guys restaurant at LaGuardia Airport, according to a Brooklyn federal court complaint.

Beginning Aug. 21, the United Federation of Teachers employee began communicating with the agent on a dating app and expressed his interest in sex — even after the undercover cop said he was 14, papers state.

He soon asked to move their chat to the encrypted messaging app Telegram for more privacy.

Seto, who sent the NYPD cop pictures of his face and genitals, said he wanted to play the role of “daddy” and sent graphic descriptions of his sexual wants.

Seto also told the agent that he wanted to watch underaged pornography with him, according to the complaint.

Hired by the UFT last year after working with the Partnerships with Children non-profit organization, Seto allegedly transmitted several videos to the agent, who said one of them appeared to feature a minor.

Telling the undercover cop “I like young” and that his age was “perfect,” Seto continued to press for a meeting for several weeks before arranging a liaison at LaGuardia Thursday evening, prosecutors said.

Officers tailed Seto from his home to the airport and arrested him at the food court, papers state.

Seto waived his Miranda rights and copped to courting the phantom teen, according to a criminal complaint.

He appeared in Brooklyn federal court Friday afternoon and did not make bail or enter a plea.

“Given the very serious nature of the allegations, Mr. Seto has been suspended without pay,” said UFT spokesman Dick Riley.