Silvio Berlusconi
However, Berlusconit will not have to serve any jail time before he has exhausted appeals.
With two appeals possible, it could be years before a verdict is final and Berlusconi lawyers announced they would file an appeal against what his counsel Niccolo Ghedini called a "completely illogical" verdict.
The verdict against the flamboyant 76-year-old media tycoon added to the complications facing Prime Minister Enrico Letta, whose fragile left-right coalition is supported by Berlusconi's centre-right People of Freedom (PDL) party.
Berlusconi was found guilty of paying for sex with former teenage nightclub dancer Karima El Mahroug, better known under her stage name "Ruby the Heartstealer", during alleged "bunga bunga" sex parties at his palatial home near Milan.
The panel of three judges, all women, also convicted him of abuse of office by arranging to have El Mahroug released from police custody when she was detained in a separate theft case.
As a result, the judges banned Berlusconi from public office.
'Bunga-bunga'
​The verdict closes a two-year trial that has mesmerised Italy with its accounts of "bunga bunga" parties at the billionaire's private villa outside Milan while he was premier in 2010.
Several PDL members have urged Berlusconi to withdraw his backing for the government, and he may be more tempted to do so if he decides it is giving him no legal protection.
"It's disgusting, a disgrace," one of his most faithful lieutenants, senior party official Daniela Santanche, told reporters in front of the Milan court.
But she said it would not impact the functioning of the government.
"We want this government to act to do the things Italians need, so this ruling has nothing to do with the ruling."
Berlusconi always denied wrongdoing and says he is being persecuted by left-wing prosecutors. He says the purported sex parties were elegant dinners where the female guests performed "burlesque" shows.
El Mahroug denies having sex with Berlusconi.
Call to police
In May 2010, the then-prime minister called a Milan police station to instruct officials to release El Mahroug, who was being held on suspicion of stealing a bracelet.
A Brazilian prostitute who lived with El Mahroug had called the premier on his mobile phone to tell him she had been arrested, prosecutors said.
Berlusconi's lawyers have said he made the call to avoid a diplomatic incident because he believed that El Mahroug, who is actually Moroccan, was the grand-daughter of Hosni Mubarak, then the Egyptian president.
The prosecution says he was anxious to cover up the relations he had with her at his sex parties.
The media magnate has recently used his own television stations to promote his version of events, with his flagship Canale 5 channel broadcasting a prime-time documentary on the so-called "Ruby Trial".
The verdict is only part of Berlusconi's legal problems.
Gambling on election
Last month an appeals court upheld a four-year jail sentence against him for orchestrating a tax fraud scheme in his business dealings – leaving him just one more appeal, at the Supreme Court, which could come within a year.
Despite Berlusconi's professions of loyalty to Letta, many analysts believe he will eventually prefer to gamble on another election, in which he could potentially become prime minister once again, rather than risk a definitive sentence.
Even if Berlusconi opts to keep backing the government, a guilty verdict would make parts of Letta's centre-left Democratic Party (PD) highly uneasy and increase the coalition's instability, according to Giovanni Orsina, professor of contemporary history at Rome's Luiss University.
"The PD would be in the same majority with a person who has been condemned in the first degree for juvenile prostitution, which is not a trivial issue," he said. "It would add up to a difficult situation." – Reuters