In a series of tweets, the 46-year-old actor replied to a Twitter user who mocked Baio for supporting US President Donald Trump.
"Ask @scottbaio what happened in his garage at his house when I was a minor. Creep," she said about her "Charles in Charge" co-star.
In the following replies to Twitter users commenting on her post, Eggert called herself a "molested child" and she was allegedly molested from the age of 14 till 17.
The two actors dated briefly while working on the 1980s show "Charles in Charge".
More From This Section
While Scott followed it saying, "I'm about to do a Facebook live to prove her claims are 100 per cent lies! #NicoleEggert."
In his video, the actor in turn accused Eggert of seeking publicity for her reality shows when she first made claims against him in 2012-13.
He said he had chosen not to respond to the allegations then. In the clip, Scott produced two letters, dated from last year, to Eggert and "Charles in Charge" co-actor Alexander Polinsky, who he claims "decided to team up against" him, telling both of them to seek police intervention if they had plausible claims.