The court will examine the verdict that found American Knox and her former lover Raffaele Sollecito guilty of killing British student Meredith Kercher in a case that has captivated the world with its sub-texts of drugs, alleged sexual debauchery and police bungling.
The Court of Cassation, which meets at 10am CET, will either uphold the murder convictions or send the case back to the appeal stage.
A decision is expected by the end of the day and could spark a request for the extradition of Knox, now 27, from the United States.
Leeds University student Kercher was found in a pool of blood in a house she shared with Knox in November 2007, half-naked and with her throat slashed.
She had been stabbed 47 times in what prosecutors initially claimed was a satanic rite.
Just under a year later, Ivory Coast-born drifter Rudy Guede was jailed for her murder, with the judge in his fast-track trial concluding that he had not acted alone.
In December 2009, Knox and Italian Sollecito were sentenced to 26 and 25 years in prison for their part in the killing.
After four years in jail, the pair were acquitted on appeal in 2011 and Knox returned to the United States.
The couple were found guilty again in a shock about-turn in January last year after judges ruled Kercher died after a row with Knox which spiralled out of control.
The Seattle native, who now works as a journalist and is reportedly engaged to a childhood friend, was handed 28 years in prison, while Sollecito was given 25 and had his passport confiscated.
The Italian, who faces immediate imprisonment if the guilty verdict is upheld, has said he will be present in court.
"We do not expect this to be the last hearing. We hope the court will annul the verdict and send the case back to appeal," Knox's lawyer Luciano Ghirga said.
He refused to speculate about a possible move by Italy to extradite Knox if her conviction is upheld. The American has said she will have to be dragged back "kicking and screaming".
Legal experts are divided as to whether an extradition request would succeed.
DNA evidence crucial
Public opinion in the US has long felt the case against Knox was flawed and that Italian detectives made mistakes – such as using dirty gloves to collect evidence – which mean the case should have been thrown out years ago.
The appeals court found the pair guilty based on DNA evidence the prosecution said linked Knox, Sollecito and Guede to the murder scene.
Sollecito's DNA was found on a bra strap the defence team says was contaminated by police incompetence.
Knox's DNA was found mixed with Kercher's blood, but in the bathroom, not the bedroom where she died, and DNA traces on the presumed murder weapon were so small they were dismissed as inconclusive by the defence.
Guede's DNA was found on Kercher's body.
Sollecito's lawyer Giulia Bongiorno said she thought the convictions would be thrown out.
"There are no (DNA) traces in the crime room, other than those of Rudy. The judges say the other traces were cleaned up, but you cannot clean selectively," she said.
Prosecutors say the stab wounds show more than one person was involved, and insist Knox and Sollecito fatally slashed Kercher while Guede held her down and sexually abused her.
The appeals court placed importance on a written confession Knox made under police questioning, in which she said she had been in the house and had heard the murder, but had not taken part.
She also initially accused a local barman of the murder, but later retracted the statements, claiming they had been made under duress.
Knox and Sollecito have provided each other with alibis, claiming they smoked marijuana and slept together at another apartment on the night of the crime.
But Sollecito admitted last year that he could not remember if Knox was present all the time.