The decision came two days after Business Insider revealed Nunberg had a long history of making provocative and racial Facebook posts.
Trump campaign manager Corey Lewandowski dismissed Nunberg as a "low-level" staffer in a phone call discussing his firing.
"Effective immediately, part-time, low-level staffer is no longer with the Trump campaign," Lewandowski said.
Nunberg's Facebook updates included one where he called Rev. Al Sharpton's daughter "N---!" and multiple posts referring to President Barack Obama as "Kenyan" and "Muslim." After Business Insider revealed Nunberg's remarks on Friday the Trump campaign said he would be fired if they were able to verify the updates were genuine.
Nunberg did not respond to a request for comment for this story on Sunday. However, in an interview with CNN, Nunberg denied writing the Facebook posts and said "anything that was posted under my name does not mean I posted it."
"I am not adept at social media," Nunberg added."I have a long record of working with diverse people. And anything you are reporting on does not reflect anything on Mr. Trump or Mr. Trump's campaign. I would also point out that all of these things were done before Mr. Trump's campaign, if I even did them - which I deny. In any event, this is the problem with
Sharpton told Business Insider he thought Nunberg's posts were "ugly" and "repugnant."
"When you refer to [Obama] as 'Kenyan,' when you refer to him in those terms and when you spell out omitting letters using an N-word referring to my daughter that's as racial as you can get," said Sharpton. "You can't get more racist than that.
Though Lewandowski dismissed Nunberg as a "low-level" staffer, campaign finance reports show he was one of only eight individuals paid by the Trump campaign between April and the start of this month. He received $15,139 during that period.
This is not the first time Nunberg has been fired by Trump, who is currently the front runner in the Republican presidential primary.
Nunberg has been working as a political adviser for Trump since at least last year. In early 2014, he was fired after urging Trump to participate in an unflattering BuzzFeed profile. He was subsequently hired again as Trump prepared to launch his presidential campaign.
Along with the comments about Obama and Sharpton, Nunberg's Facebook page included updates attacking other Republican presidential candidates. He called New Jersey Gov. Chris Christie (R) a "fat slob" and referred to Arkansas Gov. Mike Huckabee (R) as "Huckahick."
As of Sunday, the post about Sharpton's daughter, which was written in 2007, was still on his Facebook page.