In a lawsuit, Lauren Pisciotta alleges the star sent her lewd texts and performed sex acts while on the phone with her, according to US media.
She claims she was fired in 2022, but that a $3 million (£2.4 million) severance package was never paid.
The BBC has contacted West’s lawyer for a response to her allegations, but has yet to receive a reply.
The lawsuit was first reported in the US by TMZ, and later confirmed by Rolling Stone, The Wrap and US Weekly, which says court papers were filed on Monday in the US.
The BBC has so far been unable to verify the filing.
According to the documents, Pisciotta was primarily supporting herself via an OnlyFans profile in 2021 when she met West.
She says he hired her to work on the first season of his Yeezy women’s fashion line, and they ended up collaborating on three tracks from his Donda album (Pisciotta does not have any formal credits on the record, however).
West subsequently hired Pisciotta as his personal assistant, with an annual salary of $1 million (£780,000), on the condition that she was available “24-7”. She says she agreed to the terms.
According to her lawsuit, West was initially comfortable with her continuing her OnlyFans business. However, in 2022, he allegedly stated that he wanted Pisciotta to be “God like” and asked her to delete her account in exchange for a further $1 million.
After she closed the account, she claims she was bombarded with explicit text messages from West, including pornographic videos.
Pisciotta also claims he masturbated while talking to her on the phone and that, on one occasion, he pleasured himself in front of her after “trapping” her in a private room on his plane.
Around September 2022, she was promoted to Chief of Staff for his various companies, but was abruptly fired soon afterwards, her lawsuit claims. Her severance package was allegedly never paid.
In addition to sexual harassment, breach of contract, and wrongful termination, Pisciotta is also suing West and his Yeezy businesses for fraud, unpaid wages, and intentional infliction of emotion distress.
This is not the first time the rapper has been accused of lewd behaviour.
Last November, multiple employees of his Yeezy fashion line told Rolling Stone he had played pornographic films during staff meetings, and showed an intimate photograph of his then-wife Kim Kardashian in job interviews.
West has not responded to the allegations at the time, and has maintained his silence ever since.
In the past, the star has referred to a “full-on pornography addiction” that “destroyed my family”.
He once told Apple Music’s Zane Lowe that it had played a major role in his life since childhood.
“For me, Playboy was my gateway into full-on pornography addiction,” he said.
“My dad had a Playboy left out at age five and it’s affected almost every choice I made for the rest of my life.”
The star has already faced two other lawsuits this year.
In April, he was accused of racial discrimination and harassment by a former security guard at his now-closed school, the Donda Academy.
Benjamin Deshon Provo claimed he had faced discrimination because he is Muslim and was ordered to cut his dreadlocks or be fired.
West has yet to respond to the allegations.
In February, the star was also sued by the estate of Donna Summer for using a sample of her song “I Feel Love” without permission. The case was later settled out of court.
The musician was one of the most successful and prolific rappers of the 2000s and 2010s, with multi-platinum hits like Gold Digger, Stronger and All Of The Lights.
However, his recent career has been beset by controversies. Most notably, his lucrative contract with Adidas was terminated in November 2022 over antisemitic comments West made on social media.
Despite that, the star returned to the top of the US charts earlier this year both with the hit single Carnival, and its parent album Vultures.
