Kill Your Darlings, the former child star's first film at the independent-cinema showcase, premiered at the festival and puts Radcliffe into daring territory.
His young Ginsberg is initiated into drink and drugs, has sex in a library, has sex with one man and gets naked for sex with another man.
In a session with the audience at Park City, Utah, after the premiere, Radcliffe, 23, was asked if he chose the role because it fit the "weird stuff" he likes.
He conceded his tastes can run outside the mainstream.
"Films like this don't get made unless everyone involved loves them," he said.
Director John Krokidas said Radcliffe became his muse on the film and that it was clear within minutes of their first meeting that the part was his.
Krokidas said young Ginsberg starts as a dutiful son who spends his time taking care of others, but eventually spills over with repressed passion. "By the end of the movie he is a poet and a rebel," Krokidas said. "I had a feeling Dan might be able to relate to this."