The Seattle college student and her Italian ex-boyfriend, Raffaelle Sollecito, were convicted last December of murdering Knox's roommate, Meredith Kercher, a 21-year-old British student. They were sentenced to 26 and 25 years respectively.
A third man, African immigrant Rudy Guede, was sentenced to 30 years in a separate trial. His sentence was halved to 16 years on appeal.
Family and supporters of Knox and Sollecito have argued the pair's convictions were the result of judicial error, and that the only true killer is Guede, Seattlepi.com reported.
Judge Claudio Pratillo, replacing Sergio Matteini Chiari, has in the past shown a willingness to go against the judicial grain and overturn controversial convictions, something likely to give hope to Knox's supporters, Seattlepi.com said.