US rapper Flo Rida, who was sued by a NSW concert promoter for not turning up to a music festival, won't have to pay any damages because the court order was served on Facebook.

The NSW District Court ordered the singer and VIP Entertainment and Concepts to pay $380,400 in damages and $37,745 in legal fees.

He told the organisers of the 2011 Fat As Butter festival in Newcastle that he would not be performing minutes before he was meant to go on stage.

His Australian assets were also frozen, prompting the chart topping rapper to lodge an appeal.

On Tuesday, a judgment handed down by the NSW Court of Appeal found in the artist's favour, meaning he doesn't have to pay any of the money.

The original claim was served on him via Facebook because officials were unable to contact the rapper during his April 2012 visit for the Supafest tour and his Melbourne Logies appearance.

But Court of Appeal judges said "the evidence did not establish, other than by mere assertion, that the Facebook page was in fact that of Flo Rida and did not prove that a posting on it was likely to come to his attention in a timely fashion".

The judges also found that Flo Rida, whose real name is Tramar Dillard, "could have been personally served with the District Court Statement of Claim" because the evidence showed that he was in Australia at the time.

Angry fans walked out of the $110-a-ticket festival after organisers told the crowd "Flo Rida has slept in and will not be able to make the concert".

Fans also lashed out at the promoters on social media.