Among other things, De Niro purportedly used sexist language, calling female employees "c-s" and "bitches" and referred to Robinson, who was his executive assistant, as his "office wife", reports variety.com.
"Robert De Niro is someone who has clung to old mores. He does not accept the idea that men should treat women as equals. He does not care that gender discrimination in the workplace violates the law. Ms. Robinson is a casualty of this attitude," the lawsuit read.
De Niro's company filed a $6 million suit against Robinson in August, accusing her of embezzling money and binge-watching Netflix while on the job. That suit went viral with its claim that Robinson spent a four-day period in January watching 55 episodes of "Friends".
The latest round of explosive claims hit as De Niro is appearing in two major film releases - "Joker", a comic-book adaptation that opens on Friday and "The Irishman", a gangster epic that is considered to be an Oscar frontrunner.
De Niro's company, Canal Productions, is also named in the lawsuit.
In her suit, Robinson says she was underpaid compared to male colleagues and given "female duties like housework."
De Niro reportedly joked to Robinson about his Viagra prescription, asked her to imagine him on the toilet and suggested she could get pregnant using sperm from a married male co-worker.
Robinson goes on to say that in April, she submitted her resignation and had her attorney tell De Niro's team that she was contemplating a lawsuit that would address De Niro's gender discrimination and wage violations.
Robinson says her former employer's lawsuit was "replete with 'clickbait' allegations that falsely characterize her as a loafer, a thief and a miscreant. "Now, when her name is Googled, these allegations pop up on the screen. The results have been devastating to Ms. Robinson. Her reputation and her career have been destroyed," the lawsuit said.
De Niro's suit accused Robinson of charging thousands of dollars of personal expenses, including travel and meals at high-end restaurants, on the company credit card. The suit also claimed that Robinson had misappropriated $125,000 worth of frequent flyer miles.
According to the suit, she was making $300,000 a year at the time she left the company.
Robinson's suit denies those claims, and says De Niro had personally approved the disputed transactions. Robinson also denies that she "loafed" or "binge-watched" during work hours.
De Niro's representative says: "The allegations made by Graham Chase Robinson against Robert De Niro are beyond absurd."
( With inputs from IANS )