Johnny's former longtime lawyer Henry Bushkin alleges in his forthcoming biography "Johnny Carson" that the entertainer hired him decades ago to break into a New York apartment Joanne kept for herself.
Bushkin said he accompanied a gun-toting Johnny and a private investigator to the flat, then witnessed Johnny openly weep when he saw photos of Gifford all over the apartment.
Joanne, 81, denied the story in a phone interview with the New York Post Monday.
"Now I do know that Johnny was jealous of him [Gifford] because he knew that he had been a friend of mine," she said, categorizing Bushkin's story as "delusional."
She confirmed there had been a New York City apartment with some of her things in it, but insisted the flat belonged to her secretary, not her.
Joanne also said it was possible her suspicious husband broke into it, but said, "Johnny never mentioned it to me."
She doubted Bushkin's claim Johnny carried a .38-caliber revolver during the incident, however.
"Please," she said. "Johnny would have never carried a gun. First of all, he was terrified of guns. ... [Bushkin] should release it under fiction."
Johnny and Joanne divorced in 1972 after nine years of marriage.
Johnny subsequently wed two other women and died in 2005 at the age 79.
The Post said Gifford, 83, who has been married to TV personality Kathie Lee Gifford since 1986, was not available for comment on the story.