In a combative address shown on Italian television, Berlusconi insisted he was "completely innocent", describing the justice system as a "sickness", as he announced his plan to revive the party he launched when he entered politics 20 years ago.
"Whether I am deposed or not, I will always remain at your side," he declared in the 16-minute speech.
"It is not position, but popular opinion that makes a political leader. You can be in politics even if you are not in parliament."
Berlusconi's fate has taken political centre stage following a supreme court ruling last month that turned down his final appeal against a tax fraud conviction and upheld a 12-month sentence.
A cross-party senate committee has been set up to decide whether he should be ousted from parliament following the definitive criminal conviction.
The former leader cannot be removed from parliament without a full vote in the upper house.
While a hearing next month should decide whether he will be committed to house arrest or community service, the debate before the senate vote on his political status could drag on for months.
In the address, Berlusconi did not announce that he would withdraw his ministers from Prime Minister Enrico Letta's coalition government, despite threats emanating from his supporters in recent weeks.
Instead, he said ministers should put a stop to the austerity measures that were "bringing our families and our businesses to their knees", returning to the main theme of his election campaign.
The 76-year-old billionaire tycoon was dramatically ousted as prime minister in 2011 in a blaze of sex scandals and financial panic, but
re-emerged with a powerful election campaign this year that won him a third of the vote.
He is determined to avoid the humiliation of ejection from parliament and argues that a law adopted last year with the aim of cleaning up Italian politics should not apply for convictions relating to crimes committed before its adoption, as in his case.
Berlusconi says the law, approved with votes from his own party, violates his rights, and has appealed to the European Court of Human Rights in Strasbourg.
He will in any case have to leave parliament because his sentence includes a ban on holding public office while it is being served. The appeals court will rule on October 19th how long the sentence should be, within a one- to three-year timeframe.
In his address, Berlusconi called on those who voted for him to join him in the fight against "the left" by becoming "missionaries" for the relaunched Forza Italia.
Berlusconi first launched Forza Italia ("Go Italy") – named after a football chant – in 1993, winning widespread popular support, but abandoned
it in 2007 after a drubbing in the poll.