The sentence was tougher than that sought by prosecutors against the 33-year-old star over the 2015 extortion attempt, which led Benzema to be cast out of the France team for five-and-a-half years.
Benzema was not in court in the Paris suburb of Versailles for the verdict, which came hours before Real Madrid take on Sheriff Tiraspol in a Champions League game in Moldova.
He was not accused of being behind the extortion attempt but rather of conspiring with the suspected blackmailers by putting pressure on Valbuena to pay them off.
The court ruled that he had "implicated himself personally, through subterfuge and lies, to convince his team-mate to submit to the blackmail".