He was initially sentenced to four years in prison, but it was later reduced to one year due to an amnesty law.
The conviction was the 76-year-old media mogul's first in a long series of trials, but it did not mean he was going to prison right away.
Cases in Italy must pass two levels of appeal before the verdicts are final.
His lawyers declined to comment, but the billionaire businessman is expected to appeal.
Berlusconi was not in the courtroom for the verdict on the case stemming from dealings in his Mediaset business empire.
A total of 11 people were on trial. Prosecutors had alleged that the defendants were behind a scheme to purchase the rights to broadcast US movies on Berlusconi's private TV networks in his Mediaset empire through a series of offshore companies and had falsely declared the payments to avoid taxes.
Berlusconi's designated political heir as the head of the centre-right party he leads, Angelino Alfano, described the verdict as "incomprehensible" and said he was confident an appeals court would throw out the conviction.
Berlusconi has described himself as the innocent victim of prosecutors he contends sympathise with the left.
Up until now, other criminal investigations against him on charges including corruption had ended in acquittal or were thrown out for statute of limitations.
Of the other defendants, three were acquitted, including a close associate of Berlusconi, Fedele Confalonieri, chairman of Mediaset. Berlusconi and three others were convicted, including a Hollywood producer, Frank Agrama, who received a three-year sentence.
Four defendants were cleared because statute of limitations had run out.
Berlusconi, along with other defendants convicted in the case, must deposit a total of €10 million (£8m) into a court-ordered fund as appeals, which could take years, proceed.
The trial began in July 2006, but was put on hold by a now-defunct immunity law that shielded Berlusconi from prosecution while he was premier until it was watered down by the constitutional court.
The trial also faced delays as Berlusconi cited conflicts with his schedule as premier.
In the same courthouse yesterday, another criminal trial against Berlusconi was being held.
He is charged in that case with paying for sex with an under-age girl and trying to cover it up. He denies wrongdoing.
Berlusconi is not the first former Italian premier to be convicted of criminal charges.
Former Socialist premier Bettino Craxi eluded an arrest warrant and turned up at his villa in Tunisia in 1994 after a court in Italy charged him in a massive corruption case. He was tried in absentia, convicted and sentenced to eight-and-a-half years in prison. He never returned to Italy and died in exile.
Craxi was considered Berlusconi's mentor, thanks to his opening up of private television in Italy from a state monopoly.
Former seven-time Christian Democrat premier, Giulio Andreotti, was convicted of involvement in a Mafia-murder, but he was cleared on appeal and never went to jail.
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