Publicist Max Clifford has been found guilty of eight counts of indecent assault.
Clifford, 71, was cleared of a further two charges of indecent assault, with the jury failing to reach a verdict on one more additional count, after days of deliberations.
One of the girls he has been found guilty of assaulting was 15-years-old at the time of the offences in 1977.
He has also been convicted of assaulting four women aged between 17- 20 between 1978 and 1984.
The celebrity PR guru denied all the charges against him and described his life as "a nightmare" since his arrest. He added the women at the centre of the allegations were "fantasists and opportunists" who were telling a "pack of lies".
During the trial, Clifford was described as a "master in the art of intimidation", who used his celebrity connections to "bully and manipulate" girls and young women into sex acts.
The court heard Clifford convinced one 18-year-old aspiring actor she could meet singer David Bowie if she performed a sex act on him, with another promised a role in a James Bond film.
The court frequently discussed the size of Clifford's penis during evidence. He was described as being "obsessed" with how small it is, allegedly pulling down his trousers and asking one 19-year-old model "look at my penis, isn't it tiny? What can I do with it?"
He is due to be sentenced on 2 May and has been granted bail until then. The judge at Southwark Crown Court warned him that being granted bail is "no indication of what the final sentence will be".
Opening the trial, prosecutor Rosina Cottage QC described Clifford as a man who likes to "play games" who felt he was untouchable.
She added: "He is the maker of the kiss-and-tell celebrity and the breaker of reputations. He is the man called upon by television to speak about celebrity and media manipulation.
"He has been at the top of the media game for many years. He knows the strings to pull. He knows how to manipulate, lie and get what he wants."
Peter Watt, director of National Services at the NSPCC, described Clifford as a "ruthless and manipulative sex offender".
He added: "Clifford was a rich and influential man who dined with the stars but the way he manipulated and groomed his victims is typical of many sex offenders. He exploited their vulnerabilities, using lies and coercion to get what he wanted.
"Throughout the court case Clifford has behaved dismissively and arrogantly towards his victims and the suffering he has caused them. He made them go through a long and painful court case and relive their traumatic experiences by not pleading guilty."
Clifford was arrested in December 2012 under Operation Yewtree, the investigation into sex offence allegations involving Jimmy Savile and others.
Clifford is the first high profile conviction under Operation Yewtree.
Jenny Hopkins, dept chief Crown Prosecutor for CPS London, said: "Today's verdicts provide a long-denied justice to the victims of serious sexual offences."