An appeals court in Milan on Saturday ordered Silvio Berlusconi's media holding company, Fininvest, to pay compensation of 560 million euros (800 million dollars) to one of the Italian prime minister's business rivals, DPA reported.
The verdict represented the latest instalment in a long judicial process originating in 1991, when Fininvest was accused of bribing a judge in order to win a takeover battle against Carlo De Benedetti's company CIR for publisher Mondadori.
In separate criminal proceedings, Berlusconi was acquitted of corruption charges on statute of limitations grounds.
The appeals court reduced the amount that Fininvest needs to pay - 750 million euros - previously set by judges, according to Italian media reports.
CIR can now demand the money immediately. If Fininvest is unable to pay, it will have to resort to help from the banks.
The case had caused controversy earlier this month, when Berlusconi was forced to withdraw an amendment to the government's proposed budget law that would have allowed him to avoid paying the expected penalty.
The amendment would have allowed for the suspension of any payments for damages in civil law cases until a definitive verdict is pronounced by the constitutional court.
An initial draft presented by Economy Minister Giulio Tremonti last week did not contain the controversial clause, which instead appeared in a copy of the plan submitted over the weekend to President Giorgio Napolitano for approval.
Speaking ahead of Saturday's verdict, Berlusconi had said he was "certain" the appeals court would strike down the earlier ruling ordering Fininvest to pay damages to CIR.
"If the contrary were to occur, then it would represent an incredible denial of fundamental judicial principles," Berlusconi said.