Outside the court, police pushed into a crowd that had gathered to support the defendants, grabbing people and hauling them away as others shouted: "Shame!" Police said they detained about 200 people for attempting to violate public order.
Sentencing was postponed until Monday, meaning it will be revealed after tomorrow's close of the Sochi Winter Olympics, a prestige project for Mr Putin, who has faced criticism from the West for his treatment of dissenters but says he does not use the courts as a political tool.
The eight were convicted of rioting and assaulting police during an opposition protest in May 2012, the eve of Mr Putin's inauguration to a third term as president.
Two women from protest band Pussy Riot were in the crowd outside, as was Alexei Navalny, an opposition leader who is serving a five-year suspended sentence after a trial last year he said was Kremlin revenge.
Prosecutors asked for prison sentences of five to six years for the defendants, who pleaded not guilty and blame police for clashes that erupted at the rally - part of a series of protests that were the biggest of Mr Putin's long rule but failed to prevent his return to the Kremlin after four years as Prime Minister.