The verdict on what punishment she will face, expected later in the day, could upend politics in France.
Le Pen, head of the far-right National Rally, is the front-runner in opinion polls ahead of the 2027 vote.
Prosecutors have asked that Le Pen face an immediate five-year ban from public office if found guilty, regardless of any appeal process, using a so-called “provisional execution” measure.
Judges can adopt, modify or ignore the prosecutors’ request.
An automatic five-year ban would hammer Le Pen, 56, a three-time presidential contender who has said 2027 will be her final run for top office.
She would retain her parliamentary seat until the end of her mandate.
Le Pen has accused prosecutors of seeking her “political death”, alleging a plot to keep the National Rally from power that echoes claims made by US President Donald Trump about his legal woes.
Le Pen, the National Rally and two dozen party figures were accused of diverting European parliament funds to pay France-based party staff.
The defendants said the money was used legitimately and the allegations define too narrowly what a parliamentary assistant does.
However judge Benedicte de Perthuis ruled: “It was established that all these people were actually working for the party, that their [European Union] lawmaker had not given them any tasks.”
“The investigations also showed that these were not administrative errors … but embezzlement within the framework of a system put in place to reduce the party’s costs.” (Reuters)
