The 84-year-old, who was described as a “Jekyll and Hyde character” during his trial, now faces a maximum 24 years in jail.
Justice Nigel Sweeney said he would sentence Harris on Friday after considering a report on his state of health.
“Given the conviction on all 12 counts, it’s inevitable that the type of sentence uppermost in the court’s mind is a custodial sentence,” he said.
Related: Rolf Harris accused of lying to jury
The celebrity’s wife Alwen and daughter Bindi were both in court for the verdict.
Harris always denied the charges, which took place between 1968 to 1986, but he admitted during the trial to being a “touchy-feely” kind of person.
Related: Rolf Harris admits being ‘touch-feely’