A Manhattan “Shark Tank” contestant who won $100,000 for his portable dishware invention says his reputation in the business world was ruined by a nosy neighbor who falsely accused him of “running a whorehouse.”

So now former TV contestant Kyle Donovan, 46, is suing the fellow resident at his East 25th Street building for defamation.

Marina Shafrir-Zats emailed all the owners of the 12-story co-op at 11 E. 25th St. in September saying, “It came to my attention that the owner of the basement is running a whorehouse,” according to a copy of the message included in court papers.

Donovan lived in the basement unit until earlier this year, when it was sold for $1.08 million, records show. He’d been involved in a separate lawsuit with the board over the sale.

Shafrir-Zats continued in the September email that she “constantly sees women dressed like prostitutes and walking into the building and going downstairs to the basement.”

Donovan learned of the ugly accusation when the board president forwarded him a copy of the email, his Manhattan Supreme Court suit says.

“At no time did plaintiff run a whorehouse or entertain prostitutes,” he insists in court papers.

The college dropout — who recently wooed judges from the ABC show “Shark Tank” with his idea for portable dishware — says he simply had friends back to his place one night to celebrate his TV appearance.

“To be clear I have NEVER ran or been a part of ANY whorehouse, paid for any woman or had women in the basement unit or anywhere in life getting paid and servicing men or women for sex,” Donovan snapped in an email back to Shafrir-Zats.

“The thought of that is disgusting and YOU’RE disgusting for slandering me and thinking such a thing of women dressed in a way YOU don’t like,” he wrote.

“What I can promise you is that I was raised by two God-fearing women and my reputation is EVERYTHING. As GOD is my witness at some point down the line I WILL see you in court for slander. YOU can bet your VERY LAST dollar on that!!” Donovan vowed.

He says his neighbor’s accusation botched a potential deal to turn his children’s book, “The Do’Bees,” into a movie. Donovan had pitched a neighbor who’s a DreamWorks Animation executive on the idea a few months after Shafrir-Zats sent the email to the residents, including the exec.

He never heard back.

“Upon information and belief, defendant’s defamatory statement that plaintiff was ‘running a whorehouse’ impaired plaintiff’s business opportunity of developing his children’s book series into an animated film or television series,” Donovan says in court papers.

“The false accusation of ‘running a whorehouse’ is particularly damaging to entrepreneurs in the field of children’s books and entertainment,” he says.

Donovan is suing for unspecified damages.

When reached by phone, Shafrir-Zats said to a reporter, “I don’t want to talk to you.”

Her attorney later said, “We expect that Mr. Donovan’s frivolous lawsuit will be dismissed quickly.”