The Zurich-based bank was hit with a €4.5bn (£3.9bn, $5.1bn) fine, which it has already announced it will appeal.
It includes a €3.7bn penalty for UBS AG, a €15m fine against UBS (France) and civil damages worth €800m.
The case centred on accusations that UBS sent employees to solicit wealthy executives and athletes at sport or music events in France, urging them to place their money in Switzerland, reports newswire Bloomberg.
Between 2004 and 2012, it is accused of illegally concealing assets worth €10bn in Switzerland on behalf of French clients.
In a statement, UBS strongly disagreed with the verdict.
“The bank has consistently contested any criminal wrongdoing in this case throughout the investigation and during the trial,” it said.
“The conviction is not supported by any concrete evidence, but instead is based on the unfounded allegations of formers employees who were not even heard at the trial. No evidence was provided that any French client was solicited on French soil by a UBS AG client adviser to open an account in Switzerland.
“As no offence in France was established, the decision effectively applies French law in Switzerland.
“The judgement does not depart from preconceived notions, incriminating the bank based on the fact that it offered certain legitimate and standard services under Swiss law that are also common in other jurisdictions.”
The bank also strongly criticised the verdict as lacking “proof and a credible methodology for the calculation of the fine and damages”.
“The charges of laundering the proceeds of tax fraud are without merit, as the predicate offence of an original tax fraud of French taxpayers was not proven.”
The fight goes on
As stated above, UBS has confirmed it will appeal the verdict.
Under French law, this process suspends the judgement of the trial court and transfers the case to the Court of Appeals.