"I have been described as a ruthless killer but I am nothing of the sort," Sollecito told the court in Florence where he was appearing for the first time, pausing frequently during a rambling address to control his emotions.
"Amanda was my first love," he said, adding: "Amanda was carefree. She and I wanted to be isolated in our nest of desire in a little fairy tale."
"We were thinking of anything but the distorted, scornful vision of humanity of which we are being accused by the whole world," he said.
"I want you to understand how absurd the accusations against us are."
Sollecito had been on an extended holiday in the Dominican Republic, which has no extradition agreement with Italy, and his attendance had been uncertain.
"He has come to show that he is not running away," Sollecito's lawyer Luca Maori told reporters before the start of the hearing.
Sollecito said he had been in the Caribbean to "get away from the spotlight".
"I am the victim of a crazy persecution that for me has no logic and seems like an unimaginable nightmare. If this story was not real, it would be difficult to believe," he said, adding: "I don't really have a life any more."
The results of new DNA testing on a kitchen knife found in Sollecito's house were also presented at the hearing. Prosecutors allege it was one of the weapons used to kill Meredith Kercher in the home she shared with Knox.
The tests found a trace of Knox's DNA between the blade and the handle of the knife but the result is seen as inconclusive in the trial, with the defence saying it clears the couple and prosecutors saying it implicates them.
"I think that this court has all the elements to take its decision. Another court has determined why that knife was in Knox's hands," said Francesco Maresca, a lawyer for the Kercher family, who were not in court.
Sollecito's defence has already said it would be normal for the knife to have Knox's DNA since it was found in her boyfriend's kitchen drawer.
A ruling is expected later this month or next month but there is in any case one more appeal possible by either the prosecution or the defence.
Knox has lived in the United States ever since an appeals court in the university town of Perugia where the gruesome murder took place acquitted her and Sollecito of the murder in 2011 – after four years in prison.
The supreme court overturned that acquittal earlier this year, sending the case back to another appeals court for a retrial, which has so far focused on re-examining some of the DNA evidence in the case.
A third person, Ivory Coast-born Rudy Guede, is serving a 16-year sentence in prison for the murder but prosecutors say the evidence shows that he could not have been the only one to have carried out the killing.
Kercher was found half-naked in a pool of blood on the morning of November 2nd, 2007 in the university town where she was on an education exchange.
Prosecutors believe that the murder may have been the result of a sexual assault on Kercher involving Knox, Sollecito and Guede.
All three deny involvement in the crime, although Guede has admitted he was in the house at the time of the killing.