The author of a memoir about mental illness paid controversial radio host Sid Rosenberg $5,000 in “payola” cash to set up on-air interviews, a lawsuit claims.

Joseph DeBlasi says he gave Rosenberg the cash in June 2014 to secure a spot on Geraldo Rivera’s radio show in the hope of promoting his book, “Polarized: Sex, Lies, and Family Betrayal.”

DeBlasi says he met Rosenberg months earlier through a work acquaintance. Rosenberg is the controversial host of “The Bernie and Sid Show” and a regular on “Imus in the Morning,” which both air on WABC/77AM.

Rivera is also a WABC personality — “The Geraldo Show” airs every weekday.

When Rosenberg said an Aug. 13 date was set for DeBlasi’s appearance on “The Geraldo Show,” the publicity-hungry author told family and friends.

But a week before the planned appearance, Rosenberg walked back his promise, explaining to DeBlasi that “he was still working with Geraldo’s producer Marty Berman on securing the date,” the suit alleged.

Instead, Rosenberg featured the book on three separate occasions when he filled in as a guest host on the “Boomer & Carton” radio show on WFAN/660 AM, the suit says. On at least one date, he interviewed the author on-air.

DeBlasi said he never got to discuss his book on Geraldo.

Three months after the foiled “Geraldo Show” appearance, DeBlasi learned the deal was illegal, court papers claim.

“Sid was informed that his accepting $5,000 payment for Geraldo and subsequent plugs on WFAN violated FCC sponsorship rules, possibly subjecting both Joe and Sid to Department of Justice Penalties including a $10,000 fine and a year in prison,” the lawsuit says. “Rosenberg informed that Joe should just say he had been given the $5,000 back.”

DeBlasi alleges Rosenberg violated FCC laws that date back to the 1950s payola scandal — the practice of paying radio stations and deejays to play songs.

DeBlasi claims he called CBS Radio — which owns WFAN — and reported Rosenberg. An executive told him “he did not think a crime had been committed, but Rosenberg was dropped from WFAN’s schedule the next day,” the suit says.

Rosenberg’s attorney, Arthur Aidala, said DeBlasi “never” gave Rosenberg money.

“This is an absolute lie,” Aidala said. “It’s an attempt to extort money from Mr. Rosenberg.”

Aidala said CBS temporarily pulled Rosenberg from its schedule to investigate the claims in 2014, but found no wrongdoing.

“It’s quite telling that this allegedly happened four years ago and now that Mr. Rosenberg is in the running to be a morning show host on WABC, he files this lawsuit,” Aidala said.

Rosenberg was suspended in 2011 for “trying to sell on-air promotions” behind the backs of his former bosses at WQAM Radio in Miami, according to the Miami New Times. Rosenberg denied the allegations.

DeBlasi is suing Rosenberg and WFAN for fraud in Manhattan Supreme Court, and seeks $20 million.