A jury decided in 2010 that Disney hid the show's profits from its creators, London-based Celador International. The ruling Monday by a three-judge panel of the 9th U.S. Circuit Court of Appeals found no issues with the verdict or with a judge's rulings in the case.
"I am pleased that justice has been done," Celador Chairman Paul Smith said in a statement.
Disney did not immediately comment on the decision.
The jury found that Celador was owed $269.2 million, and a judge later added $50 million in interest to the judgment.
The appeals court determined the verdict was not "grossly excessive or monstrous" and that it was not based on speculation or guesswork.