Rolf Harris has been found guilty on 12 charges of indecent assault against four girls, from 1968 to 1986.
Mr Justice Sweeney said a jail term was “uppermost in the court’s mind” but he would hear evidence as to Harris’ state of health before sentencing on Friday.
The trial began in early May, when prosecutor Sasha Wass QC told the jury Harris was a ‘Jekyll and Hyde’ character whose immense talent and popularity hid a dark side: he was sexually attracted to young girls.
However the defence – and Harris himself – denied all the charges, saying his accusers were lying, their stories inconsistent and unbelievable.
Both Harris' wife Alwen and daughter Bindi were in court to hear the verdicts.
READ MORE: Key moments from the trial
The Harris family gasped and some held hands in the public gallery as the verdicts were announced.
Alwen was comforted by family members in a side room afterwards, and Bindi was in a supportive embrace with Harris' long-time publicist Jan Kennedy.
Rolf Harris himself sat without obvious emotion, and gave a brief wave to his family as he walked out of the court with his lawyers.
Fairfax understands, from a source close to the Harris family, that the entertainer was "in shock" after the verdicts were handed down.
Later, he made his way slowly from the court, hand in hand with his wife and daughter, and was driven away in a black car without making any statement to the media pack.
The entertainer may also face charges in Australia, if police decide to take action over the allegations made by Australian witnesses during the trial and others who came forward too late to take the stand.
Scotland Yard said they had received a number of new allegations and these were now being considered.
"Rolf Harris has habitually denied any wrong doing forcing his victims to recount their ordeal in public," Detective Chief Inspector Michael Orchard said.
"He committed many offences in plain sight of people as he thought his celebrity status placed him above the law.
"I want to thank the women who came forward for their bravery, I hope today's guilty verdict will give them closure and help them to begin to move on with their lives."
Peter Watt, director of national services at the NSPCC, said the charity was "delighted to have played a major role in helping bring Rolf Harris to justice and to uncover the dark side of an entertainer who hid behind his happy-go-lucky persona while committing sexual offences".
Jenny Hopkins, Deputy Chief Crown Prosecutor for the CPS in London, said: "Rolf Harris used his status and position as a world famous children's entertainer to sexually assault young girls over a period spanning 18 years."
"The victims in this case have suffered in silence for many years and have only recently found the courage to come forward. I would like to pay tribute to the bravery they displayed in coming to court and giving evidence. That bravery and determination has seen Rolf Harris brought to justice and held to account.
"Each victim, unknown to the others, described a similar pattern of behaviour; that of a man acting without fear of the consequences.
"The prosecution of sexual offences is often difficult and complex, perhaps even more so when the allegations are from some years ago. We will continue to consider cases and wherever there is sufficient evidence and it is in the public interest, we will work with police and victims to build strong cases which can be put before a court.
"I hope today's verdict provides other victims with the courage and confidence to come forward no matter who is alleged to have carried out the abuse and when."
An emotional Vince Hill, friend to Harris, told the BBC he felt "defeated" by the verdict - he had been planning a surprise party on the assumption Harris would be acquitted.
And choreographer Dougie Squires, who gave evidence of Harris' good character during the trial, said he was shocked by the verdict.
"I felt the man I knew couldn't be a paedophile," he said.
Britain's National Society for the Prevention of Cruelty to Children said it had received "28 calls about Rolf Harris through our helpline. This included 13 people who said they had been abused by him".
The BBC reported that Harris could lose his CBE, as normal protocol sees honours from Buckingham Palace forfeited when the recipient is considered to have brought the system into disrepute.
He will also lose his BAFTA Fellowship honour from the British Film industry, a spokesman from the organisation said.
The entertainer's website rolfharris.com was taken off the internet after the verdict, reportedly due to a flood of abusive comments.
Harris can be sentenced to a maximum of two years' jail for each guilty verdict, according to UK law as it was before 1988.
Under sentencing guidelines, the two of the 12 charges that do not involve touching the genital area would be punished by a maxiumum of 18 months' jail.
Harris’ PR agent sent out a brief message saying neither his legal team nor his family would comment on the verdicts.
The 84 year-old entertainer will remain on bail pending a medical report before his sentencing on Friday.