The former conservative president, 70, was found guilty of criminal conspiracy over efforts by close aides to procure funds for his 2007 presidential bid from late dictator Muammar Gaddafi.
He was acquitted of all other charges, including corruption and receiving illegal campaign financing.
Sarkozy's prison sentence was enforced immediately because of the "extraordinary seriousness" of the crime, judge Nathalie Gavarino told the court.
He was incarcerated at La Sante prison in Paris last month - a stunning downfall for a man who had led France from 2007 until 2012.
Sarkozy has consistently denied wrongdoing and has appealed, calling himself a victim of revenge and hatred. He will not attend the hearing but be represented in the appeals court by lawyers.
Attorney Christophe Ingrain said after Sarkozy went to jail that his client did not meet any of the legal justifications for "provisional detention", and had always abided by the judicial process.
In French criminal law, those justifications include the need to prevent a continuation of the crime or to ensure that the accused remains available to the justice system.
If the court agrees to release him, Sarkozy could be required to wear an electronic tag, deposit a sum of money or check in regularly with authorities.
Sarkozy has faced several legal battles since leaving office. Last year, France's highest court upheld a conviction for corruption and influence peddling, ordering him to wear an electronic tag for a year, a first for a former French head of state. The tag has now been removed.
Also last year, an appeals court confirmed a separate conviction for illegal campaign financing over his failed re-election bid in 2012. A final ruling from France's highest court is expected on that case this month.
