The court in Pskov, north-western Russia, delivered its verdict on Monday.
It found Shlosberg guilty of “public actions aimed at discrediting the use of the armed forces of the Russian Federation”.
The prosecution had demanded 12 years and one month in jail. The criminal charges were brought following Shlosberg’s comments published on social media.
In his closing speech, Shlosberg again rejected all the charges, describing the trial as “an imitation of an investigation” in order to “achieve an obviously illegal goal”, according to a transcript published by the Novaya Gazeta newspaper.
The opposition politician also repeated his call for a ceasefire in the Russia-Ukraine war and the start of a “political dialogue”.
He was repeatedly interrupted by the presiding judge.
Yabloko was struck off the ballots earlier this month over accusations that the party publicly supports the “international LGBT movement”, which Russia’s Supreme Court designates as extremist.
A lawsuit brought forward by pro-Kremlin nationalist party Rodina also argued that Yabloko was guilty of copyright infringement.
Yabloko rejects all the accusations.
All 10 other parties taking part in the 18-20 September election support the war in Ukraine.
The latest ratings of the ruling United Russia slipped to 32.1% earlier this month – the lowest figure since May, according to Russia’s state-owned pollster VCIOM.
Still, the Kremlin is widely believed to have the resources to deliver the outcome it wants at the election.
Independent election watchdogs have been deprived of much of their ability to monitor and challenge the process.
