Berlusconi, 77, maintains the tax fraud conviction, which Italy's supreme court upheld during the summer, is politically motivated by left-wing elements in the judiciary who want to remove him from Italian politics.
"I am absolutely sure that the end of these actions will be the reversal of the judgment, with my full acquittal," he said at a rally with supporters before the Senate voted.
Berlusconi was convicted Aug. 1 with several other defendants of using offshore companies in tax-haven countries to buy movie rights for his TV networks and grossly inflating the payment amounts to avoid $502 million in taxes.
A court found he was the "creator of the mechanism for twisting [film] rights."
The former prime minister said Tuesday an affidavit from a former U.S. business associate would clear him of the charge, and he would ask for a legal review of the conviction, the Italian news agency ANSA reported.
Berlusconi has said his ejection would be a "coup" and has expressed anger the Democratic Party backed the effort to strip him of his parliamentary seat, accusing the party of "political homicide."
Prime Minister Letta's Democratic Party and the anti-establishment 5-Star Movement backed the decision to eject Berlusconi, the ANSA news agency reported.
His center-right Forza Italia party withdrew its support for Letta's left-right coalition government and joined the opposition Tuesday.
"I am persecuted," Berlusconi said. "Parliament should not cede its sovereignty to an uncontrollable judiciary."
The Senate received at least 13 petitions against taking away the Senate seat from Berlusconi, sources told ANSA.
He was sentenced to four years imprisonment, but three years were automatically pardoned, along with a public office ban for two years. Because he is older than 70, he was exempted from imprisonment and instead must do community service.