The murder of 21-year-old Kercher sparked lurid headlines around the world, notably in Britain, fed by rampant rumours as well as repeated leaks to the press during the investigation.
Kercher's body was found in a pool of blood with her throat slit in the bedroom of the house she shared with Knox while the two were studying at Perugia's prestigious University for Foreigners.
Prosecutors accused Knox of persuading Sollecito and Rudy Guede, an Ivory Coast citizen, to take part in an extreme sex game involving Kercher, which turned violent and led to Kercher's death.
Guede was sentenced in October 2008 to 30 years in jail for taking part in the murder.
Knox said as part of her defence that she and Sollecito had watched a film at his home the evening of the murder, smoked marijuana and had sex.
Sollecito had originally said he could not remember if Knox was at his home, but later said she was.
Guede, who is appealing his conviction, said he was in the house the night of the murder but did not kill Kercher.
The media focused much of its attention on Knox, portrayed as a wholesome girl-next-door by her defenders, and a cold, duplicitous "she-devil" by her accusers.
|Lawyers for Knox and Sollecito said they
would appeal the verdict [AFP]
Following the verdict Janet Huff, Knox's aunt, told American news network CNN that the family was "crushed" by the verdict.
Asked what had "most damaged" Knox's case, Huff said: "The media from the get-go was fed false information and they ran with it ... Boy, is it a sexy story: beautiful, young American girl caught up in this horrible nightmare."
As the judge read the verdict, Knox burst into tears and hugged her lawyer. She and Sollecito were then taken to prison, where they have spent the past two years.
Francesco Maresca, a lawyer for the Kercher family from Coulsdon in southeast
England, welcomed the sentence.
"With tonight's verdict, justice has been done for the tragedy which struck the Kercher family. They are satisfied," he said.
Outside the courthouse, Luciano Ghirga, Knox's lawyer, told journalists: "There is contradiction between the weakness of the proof and the gravity of the crime."
Prosecutors alleged small traces of DNA matching Kercher's were found on the blade of a knife, washed with bleach, at Sollecito's home.
The defence said the knife did not match Kercher's wounds and that the DNA evidence was too small to be conclusive and might have been contaminated.
Knox has also been convicted of slandering Patrick Lumumba, a bar owner who she said had been at the scene of the crime.
Lumumba was briefly arrested but then cleared.
Asked by the media if he would fight on, Knox's father, replied: "Hell yes."