A judge sentenced Benzema to one year in prison with a one-year suspension and ordered him to pay a €75,000 (£63,000; $84,000) fine.
Benzema, 33, was one of five persons charged last month in connection with an extortion attempt on Frenchman Mathieu Valbuena.
The controversy shook the French football community, and both players were stripped of their national team spots.
The issue began in June 2015, when the two footballers were attending a training session in France.
Prosecutors claim that at the camp, Benzema placed pressure on Valbuena to pay up the blackmailers with whom he had arranged to act as a middleman.
Benzema has consistently disputed the charges, claiming he was merely attempting to assist Valbuena in removing the damning film.
The midfielder has subsequently returned to the France team and is scheduled to start for Real Madrid against FC Sheriff Tiraspol in the Champions League on Wednesday night.
Benzema, who plays for the Greek club Olympiakos, was not present in court in Versailles for the ruling, nor was Valbuena.
On Wednesday, four of Benzema's co-defendants in the trial were also found guilty. They were sentenced to prison terms ranging from 18 months suspended to two and a half years.
Benzema's attorneys have stated that he would fight his conviction. "Ultimately, the reaction is an indignant one to this judgment, which is completely inconsistent," his lawyer, Sylvain Cormier, told reporters outside court.
However, the court stated in his decision that Benzema "implicated himself directly, via subterfuge and deceit, to urge his teammate to accede to the blackmail."
Benzema made an unexpected return to the French national team in May, five years after he was banished from the squad following the initial claims in 2015.
However, the French football association stated last month that a guilty conviction would not necessarily jeopardize Benzema's place in the national team.
Benzema has been in excellent form since being recalled by France boss Didier Deschamps, netting nine goals in 13 outings for his nation. He has also scored 10 goals for his team, Real Madrid, which has yet to react on the ruling.
Benzema has been declared a candidate for the Ballon d'Or footballer of the year award, which will be revealed next week.
It all started in 2015, when Valbuena, now 37, requested Axel Angot, a guy from Marseille, to transfer the contents of his phone to a new device.
Mr. Angot discovered sexually explicit content on the phone. Mustapha Zouaoui, another defendant in the trial, is accused of attempting to blackmail Valbuena by threatening to make the recording public.
Mr. Zouaoui told reporters that while he had shared the footage, there had never been an effort to extort money from him.
Valbuena stated that he was approached by another defendant, Younes Houass, who informed the court that he had warned the player about the problem without asking for money.
When the footballer approached the cops, they organized a sting operation including an undercover agent.
Prosecutors said that another defendant, Karim Zenati, Benzema's boyhood buddy, was subsequently pulled into the scheme. Prosecutors alleged that at this time, Benzema was requested to participate as a "middleman" in the plot.
Benzema addressed his fellow France player in his hotel during the national team's training camp in October 2015.
Benzema said he was only attempting to assist his buddy in disposing of the obscene tape, warning him, "Be cautious, Math, they're huge, big goons."
He then promised to connect him with someone he could rely on: his boyhood buddy, Mr Zenati.
When the footballer approached the cops, they set up a sting operation that included an undercover agent.
Prosecutors said that another defendant, Karim Zenati, Benzema's childhood friend, was later drawn into the plan. Prosecutors said that at this point, Benzema was asked to act as a "middleman" in the conspiracy.
Benzema spoke to his French teammate in his hotel during the national team's training camp in October 2015.
Benzema said he was merely trying to help his friend dispose of the obscene film, telling him, "Be careful, Math, they're large, big guys."
He then vowed to put him in touch with someone he could trust: his childhood pal, Mr Zenati.
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