Police tracked him to a hotel in Venzone, a town in northeast Italy near the Austrian and Slovenian borders, just hours after an appeal court in Florence sentenced him to 25 years in prison, a source at the police station in the nearby city of Udine told AFP.
"Police went to find him in his hotel and he followed them willingly" back to the police station, the source said.
"He is still there now. He is not under arrest. He has to hand over his passport, which can be a lengthy process," he added.
Sollecito was reportedly staying with his girlfriend Greta Menegaldo, who comes from the city of Treviso according to Italian media reports - over 150 kilometres from Venzone.
The 29-year-old had been ordered to surrender his passport and driving license by the court, which said it considered him a flight risk after upholding his conviction on Thursday evening for the murder of Meredith Kercher, stabbed to death in 2007.
Dressed in a blue sailor jacket and wearing sepia-coloured aviator sunglasses, Sollecito had attended a court hearing earlier on Thursday, but was not present for the verdict and was reported to have already left Florence.
Knox and Sollecito were first convicted of the murder in 2009, then acquitted in 2011 on appeal.
The supreme court last year ordered a re-trial, leading to the guilty verdicts issued on Thursday.