A Broadway pianist is a pedophile, the Queens DA said Friday night.

Musician and vocal coach Justin Brown, 26 — who has worked as a rehearsal pianist for “Dear Evan Hansen” and “King Kong” — was arrested Thursday when he showed up at a Queens address with his backpack filled with lubricant and condoms, prosecutors said.

Brown thought he was meeting a 14-year-old boy for sex, prosecutors said.

In fact, the “boy” was an undercover NYPD cop who’d posed as a kid on the dating app Grindr, prosecutors said. In custody, Brown allegedly admitted that he’d been chatting with several underage boys.

He was ordered held in lieu of $20,000 bail at an arraignment in Queens Criminal Court.

“The defendant, who was told numerous times that the person he was chatting with was an underage boy, continued to pursue the ‘youngster’ and traveled from Manhattan to Queens to meet for sex,” said Queens Acting District Attorney John M. Ryan.

Brown was using the dating app Grindr at 11 a.m. on Monday, Sept. 2, when he started a back-and-forth with the “boy.”

He asked the kid’s age, was told “14,” and responded, “Ha-ha nice,” according to the criminal complaint against him.

Brown then “asked about switching over to the Snapchat app,” the DA said in a press statement.

“Around noon that same day on Snapchat, the “teenager” received a message from Brown using the name “jbplaysmusic1.” A sexually explicit conversation ensued, and the defendant allegedly sent a photo of his face and a picture of his penis to the “boy.”

The two had numerous sexually explicit conversations between Monday and Thursday, prosecutors said.

Brown faces up to seven years in prison on charges of attempted use of a child in a sexual performance, second- and third-degree attempted criminal sexual act, first-degree attempted dissemination of indecent material to minors and attempted endangering the welfare of a child.

In addition to playing for rehearsals for “Dear Evan Hansen” and “King Kong,” Brown, who lives on the Upper West Side, has worked as a music director and pianist on numerous off-Broadway productions, according to his online resume.