Vivendi said in a statement it would appeal the verdict, which said it could be liable to pay up to $956 million (€765 million) to the US firm headed by magnate John Malone. The damages will be awarded at a later phase in the case.
A Liberty Media statement said the case stemmed from "breach of contract and fraud" by Vivendi and that damages could be awarded after post-trial proceedings.
"Although Liberty expects the defendants to ask the court to set aside the verdict during this process, Liberty is confident that the court will deny that request and that the jury's decision will stand," Liberty said.
Vivendi said it "strongly disagrees with the decision" and "believes that there are many grounds for appeal."
Liberty Media, which owns a variety of assets including the Starz movie channel and has stakes in SiriusXM radio, Time Warner and Viacom, ended up as a Vivendi shareholder in 2001 because of its interest in USA Networks, a broadcaster bought by the French firm.
Liberty sued in 2003, contending the shares used in the acquisition were overvalued and inflated because of fraudulent statements by Vivendi about its financial conditions.
The deal came when Vivendi was undergoing a massive expansion led by its flamboyant chief Jean-Marie Messier, who was ousted in 2002.
It is the latest in a long litigation battle with Vivendi in the US courts.
In 2010, a jury said Vivendi recklessly misled investors about the company's finances, opening the door to a potential multibillion dollar payout to shareholders. But that case remains pending on appeal.
Messier was cleared in that case with his chief financial officer Guillaume Hannezo by the jury.
But a French criminal court in 2011 handed Messier a three-year suspended jail term over a fraud scandal that nearly brought down the group in 2002.
Messier received the suspended term on charges including embezzlement after he awarded himself a multimillion dollar payoff, without board approval, when he left the group in 2002.
Vivendi and Messier had been accused of making false statements about company finances between 2000 and 2002, before a collapse of the group's share price in the lawsuit charging "recklessly misleading communication."
Liberty Media in 2001 accepted 37 million Vivendi shares priced at 50 dollars in a deal which made the US firm the second largest shareholder in Vivendi.
The transaction was finalized in May 2002, days after Moody's downgraded Vivendi's credit rating because of its hefty debt.
Vivendi shares lost 80 percent of their value in 2002.
Vivendi now controls video game giant Activision Blizzard, Universal Music Group, French telecom operator SFR and entertainment firm Canal Plus along with other operations around the world.