"I feel obliged to stay in the (political) field to reform the planet justice," the media tycoon told TG5, one of the television stations he runs, after branding Friday's verdict an "intolerable" political ruling.
"There are going to be consequences," declared 67-year-old three-time Prime Minister who first burst on to the Italian political scene almost two decades ago.
A Milan court on Friday sentenced Berlusconi to four years in jail -- quickly reduced to one year under an amnesty law designed to tackle overcrowding in prisons -- and banned him from holding public office for five years.
The three-time premier had announced on on Wednesday that he would not run in the next election due in the spring but did not say he was withdrawing completely from political life.
"I will not be presenting my candidacy but I will remain at the side of younger people who can play and score goals," he said.
Italy's press nevertheless on Saturday declared that the Berlusconi era was at a definitive end, with one observer drawing a parallel to the fate of US gangster Al Capone.
Berlusconi's lawyers said they would lodge an appeal by November 10, and Italy's lengthy appeals process will likely enable him to stave off both prison and political banishment.
"And so ends a Titanic affair, born in television and finished in court, with a clear, very tough and above all insulting punishment," wrote centre-left daily La Repubblica's editor, Ezio Mauro, retracing Berlusconi's political trajectory from "supreme domination" to his "fall from grace and definitive decline".
"An entire generation of Italians born after 1975 will for the first time vote in elections next spring that are not a pro- or anti-Berlusconi referendum," said the influential daily La Stampa. "The mirages and alibis are finished," it declared.
Left-leaning daily Il Fatto Quotidiano, which had waged war on Berlusconi's government during his three stints as prime minister between 1994 and 2011, ran a triumphant headline quoting the court's verdict that the media tycoon had a "natural capacity for delinquency".
The conviction "is the proof that Italy was governed for nine years by a tax cheat," said the paper.
"He falls like Al Capone"
"In the end he falls like Al Capone," Carlo Maria Pinardi, professor of finance at Milan's Bocconi University, told AFP, referring to notorious Chicago gangster who was finally jailed not for the many major crimes he committed but for tax fraud.
Pinardi played down the scale of Berlusconi's offences, saying that "many great Italian entrepreneurs have done worse, with the help of their tax advisers and accountants."
But "Berlusconi is finished. If the past, symbolised by this comic opera character, could be wiped out, the country would have much to gain", he said.
For Pinardi, with new Prime Minister and former European Commissioner Mario Monti there was no doubt that Italy now showed a new face: "a serious, respectable person, of a quality superior to European politicians."
Berlusconi's lawyers said Friday that they would lodge an appeal by November 10, according to media reports, automatically suspending the application of the sentence while Berlusconi's reaction to the ruling was defiant.
During the trial, which began six years ago but was repeatedly suspended, Berlusconi was accused of artificially inflating the price of distribution rights bought by his Mediaset empire and of creating foreign slush funds to avoid paying taxes in Italy.
The court also sentenced the media tycoon and 10 co-defendants to pay 10 million euros ($13 million) to Italian tax authorities for losses in what they called "large-scale fraud".
"This is an incredible and intolerable political sentence. This is no doubt a political verdict, as political as all trials fabricated against me," post-war Italy's longest serving prime minister said on his Italia 1 television channel.
The prosecution had asked for a prison sentence of three years and eight months for Berlusconi, who also owns the AC Milan football club.
Friday's sentence came a week after Berlusconi denied in a separate case that he hosted raunchy parties and paid for sex with then 17-year-old exotic dancer Karima El-Mahroug, better known as "Ruby the Heart Stealer".
The sex trial was one of the last in a series of scandals that helped precipitate Berlusconi's downfall in November 2011, which was finally triggered by a parliamentary revolt against him and a wave of panic on financial markets.
He was sentenced three times to a total six years and five months in prison in 1997 and 1998 for corruption, forgery and illegal party financing. The sentences were later scrapped by higher courts or fell under the statute of limitations.
Italian media and judicial officials widely expect the statute of limitations to kick in as soon as next year, which would imply that higher appeal courts will not even have to take on the case.