The former It's A Knockout presenter was cleared last week of 15 counts of rape in relation to two women who claimed they were sexually assaulted by him between 1976 and 1981.
The 84-year-old was convicted by the jury at Preston Crown Court of indecently assaulting one of the complainants when she was under the age of 16, and had earlier pleaded guilty to another indecent assault on the same girl when she was 13.
The charge Hall admitted involved an incident at a dinner party where he crept into his victim's bedroom and assaulted her.
The married father-of-two is currently serving a 30-month jail term after he pleaded guilty last year to indecently assaulting 13 other young girls, aged between nine and 17, over a 20-year period.
The ex-BBC Radio 5 Live football match commentator had not been due for release from that custodial sentence until September.
Hall will not now be eligible for release until December 2015.
The new sentence will only begin after the end of his current jail term.
Passing sentence, Lord Justice Turner said of his offences: "It was an act of vile bravado and horrible betrayal."
Hall, wearing a dark suit, white shirt and striped tie, was excused from standing as sentence was passed.
He sat impassively in the dock, with his head bowed, his legs crossed and his hands resting on his lap as he listened to the proceedings.
The victim of his latest offences sat yards away and began wiping away tears as details of the offences given.
The judge said one of the aggravating factors of the offences was Hall's initial public denials of guilt.
Hall was sentenced to 12 months for the offence he admitted and was given an additional 18 months for the indecent assault of which he was convicted by the jury.