Tymoshenko and her attorneys said Thursday they plan to instead take their case to the European Court of Human Rights, which says it will make the case a priority because of what it called the "serious and sensitive nature of the allegations raised," Voice of America reported.
Kiev's Court of Appeals upheld Tymoshenko's seven-year prison sentence for abuse of power in signing gas-supply contracts with Russia in 2009, Russia's Interfax News Agency reported.
In a statement, Tymoshenko referred to appeals in the Ukrainian court as "this shameful process."
She was sentenced in October over the gas deal, which some of her opponents said benefited Russia too much, and she faces other charges.
But her conviction has been condemned as politically motivated by the United States, the European Union and human rights groups, and on Wednesday Ukrainian President Viktor Yanukovych said he does not oppose the release of Ms. Tymoshenko.
The EU, which Ukraine wants to join, said Monday it won't sign a political and trade cooperation deal until the country resolves Tymoshenko's case.
Tymoshenko has labeled her trial "a political lynching" to enable Yanukovych to eliminate her as the main opposition candidate in an election next year. Yanukovych denies the claim.