The 73-year-old Academy Award-winning actor was one of many well-known stars to take part in a video campaign in order to encourage people to vote ahead of the election next month.
When asked in front of a camera “What do you care about?”, the Godfather Part II actor let loose in an impassioned rant against the Republican politician.
He said of Trump: “He’s so blatantly stupid. He’s a punk, he’s a dog, he’s a pig, he’s a con, a bullshit artist, a mutt who doesn’t know what he’s talking about.”
De Niro, star of such films as Taxi Driver, Raging Bull and Goodfellas, said that Trump “doesn’t do his homework” and that he “doesn’t care”.
He added: “Colin Powell said it best, he’s a national disaster, he’s an embarrassment to this country, it makes me so angry that this country has gotten to this point that this fool, this bozo, has wound up where he has.
“He talks about how he wants to punch people in the face. Well, I’d like to punch him in the face.”
De Niro concluded: “This is somebody that we want for president? I don’t think so. What I care about is the direction of this country, and what I’m very, very worried about is that it might go in the wrong direction, with someone like Donald Trump.
“If you care about your future, vote for it.”
The clip was produced by Anonymous Content for their #VoteYourFuture effort but it was not used in the final edit of the star-studded campaign.
Instead, the testimonial was unveiled on US TV programme The Kelly File, hosted by Megyn Kelly on Fox News, and it has since become a viral success.