Hall, 84, made no reaction as he was convicted of one indecent assault but cleared of 15 rapes and four other indecent assaults by a jury of eight women and four men following seven hours and 15 minutes of deliberations.
At the start of the trial he had pleaded guilty to one other count of indecent assault.
The former BBC broadcaster mouthed 'Thank you' to the jury at Preston Crown Court at the end of the two-week trial as he was led away to the cells to continue serving his sentence for earlier offences.
Hall will be sentenced for the one charge he was convicted of next Friday.
The former It's A Knockout presenter was taken from custody in Leyland, Lancashire, last October and was questioned about allegations from the two complainants who came forward after his conviction last year for sexually abusing girls.
He was then charged with numerous counts of rape and indecent assault, which he denied.
Both girls and their families were known to the defendant.
The offences were alleged to have taken place between 1976 and 1981.