On October 30, 2017, adult film actress and reality television personality Ariane Bellamar made accusations via Twitter, that Piven had groped her. The next day, Piven responded to these allegations writing, "I unequivocally deny the appalling allegations being peddled about me. It did not happen". Cassidy Freeman came to Bellamar's defense in an Instagram post, alluding to her own troubling past with Piven, who the actress claims engaged in "predatory behavior" toward her when she was "far too young". On November 9, advertising executive Tiffany Bacon Scourby alleged that Piven had attacked her in 2003, stating that he had "jumped on" her, "exposed his genitals, held her hands down and began rubbing against her body until he ejaculated". Piven responded to the allegations, calling them "absolutely false and completely fabricated". A representative for Piven said the actor was "looking at legal options".
On November 13, 2017, Piven voluntarily took a polygraph test in which he was asked a series of questions about each allegation, which allegations he again denied. He passed the test with "no signs of deception". The polygraph test was administered by a member of the American Polygraph Association.
Later that month, Anastasia Taneie, who worked as an extra on Entourage, alleged that Piven "confronted her in a dark hallway and groped her breast and genitals as he forcefully pushed her against a wall". On November 27, 2017, CBS decided not to order a full season of Wisdom of the Crowd, following weak ratings and allegations of sexual harassment involving Piven. In January 2018, BuzzFeed published an article in which three more women accused Piven of "sexual misconduct or inappropriate behavior". They alleged Piven pinned down one woman on a couch after following her to her trailer on the set of a film in 1985, engaged in "physically aggressive" behavior with another while on a date, and attempted to force himself on the third woman in a hotel room around 1994. BuzzFeed News corroborated the stories with eight people who said the women had shared the encounters with them in the years since. Piven "vehemently denied" all the allegations, and his lawyer called them "works of fiction", saying they were opportunistic efforts to "obtain attention and/or money". Piven submitted a written statement to BuzzFeed, in which he referred to the lie detector test he had taken and asserted: "I have never forced myself on anyone, nor have I ever exposed myself or restrained anyone against their will. To the contrary, if any woman ever said no, I stopped".