Berlusconi, 76, has also been banned from public office after he was found guilty of giving Karima El Mahroug money for sex when she was just 17.
The flamboyant media tycoon will appeal, having already done so against a previous conviction for tax fraud.
He was also found guilty of using his power as then-PM to have El Mahroug released from police custody after she was detained for theft.
Berlusconi reportedly told police she was the granddaughter of former Egyptian president Hosni Mubarak. El Mahroug is Moroccan.
The former Italian PM, whose notorious 'Bunga Bunga' parties enraged Italians feeling the pinch of a global recession and budget cuts, was said to have paid El Mahroug - known as 'Ruby the Heart Stealer' - both for sex and her presence at events hosted at Berlusconi's mansion.
Berlusconi denied that the infamous parties were of a sexual nature, trying to claim payments made to women were 'gifts' between friends.
More serious though was the charge that he abused his power to have El Mahroug released after she was arrested on suspicion of theft, claiming that her being held would cause a diplomatic incident when she was in no way connected to the since-ousted Egyptian president.
Berlusconi's lawyer, Niccolo Ghedini, immediately announced an appeal, describing the sentence as "beyond reality".
He will not see jail until the process is exhausted, which could take some years.
Last October, Berlusconi was sentenced to four years in prison for tax fraud connected to his television channels.
The case is now heading to Italy's highest court for a final appeal, after his defence team failed to have the verdict overturned at the constitutional court.
- Society & Culture
- Crime & Justice
- Karima El Mahroug
- Bunga Bunga
- president Hosni Mubarak