"Ultimately we are pleased with the decision, pleased that we've got a decision, but it's not a time for celebration," Lyle Kercher, the victim's brother, said.
Kercher's sister, Stephanie, said the verdict "does bring a a little bit of justice, for us and for her."
"Life will never be the same without Mez," she said.
Kercher, 21, was Knox's roommate while they studied in Perugia.
Her body was found in a pool of blood with her throat slit on Nov. 2, 2007 at the apartment they shared. Prosecutors said the Leeds University student was murdered the previous night.
Knox, family react to verdict
As soon as the judge read the verdict just after midnight following some 13 hours of deliberations, Knox began weeping and murmured, "No, no," then hugged one of her lawyers.
Minutes later, the 22-year-old Knox, who is from Seattle and the 25-year-old Sollecito, were put in police vans with sirens blaring and driven back to jail.
Prosecutors had sought life imprisonment, Italy's stiffest sentence. Courts often give less severe punishment than what prosecutors demand.
The American's father, Curt Knox, asked if he would fight on for his daughter, replied, with tears in his eyes: "Hell, yes."
amanda knox verdict