Seven of the “Bolotnaya” activists received prison terms of up to four years. An eighth, the only woman on trial, received a suspended sentence.
Outside the court in Moscow, police detained about 200 people who rallied in support of the defendants.
The activists were convicted on Friday.
But the judge delayed sentencing until Monday – sparking speculation that the Kremlin was trying to avoid negative publicity ahead of Sunday’s closing ceremony for the Sochi Winter Olympics.
Amnesty International called Friday’s guilty verdicts a “hideous injustice” which came at the end of a “show trial”.
About 650 activists were detained following clashes with police at an anti-Kremlin protest in Moscow’s Bolotnaya Square, a day before Mr Putin was due to be sworn in for a third term as president in May 2012.
Criminal proceedings were subsequently started against 28 individuals.
During Monday’s hearing, the accused men were held handcuffed in a cage.
Sergei Krivov, Artyom Savyolov, Stepan Zimin, Aleksei Polikhovitch, Andrei Barabanovto, Yaroslav Belousov and Denis Lutskevich were jailed for between two-and-a-half and four years.
An eighth activist, Alexandra Dukhanina, the only woman on trial, was given a suspended sentence.
All have been in custody since their arrest except for Dukhanina, who was held under house arrest.
Prosecutors had requested jail terms of five to six years.
Yaroslav Belousov – who received a two-and-a-half-year sentence – claims a yellow spherical object he is accused of throwing at police was just a lemon.
His lawyer, Dmitry Agranovsky, said the sentences were excessive.
“The sentences are harsh and inappropriate. They were issued based on the political situation, not on the nature of the charges,” he said, according to the AFP news agency.
But AFP quoted Judge Natalya Nikishina as saying that the defendants “took part in mass riots; their shared blame is established and proved”.
Among the protesters detained outside the court on Monday were Nadezhda Tolokonnikova and Maria Alyokhina, members of protest group Pussy Riot and fierce critics of Mr Putin, who were recently released from prison under an amnesty.
Many of the protesters chanted “freedom” and “Maidan”, in a show of solidarity with the activists in Ukraine’s Independence Square, also known as the Maidan.
However, opposition leader Alexei Navalny distanced himself from events in Ukraine, saying that Russian had its own battle for freedom.
“Maidan is not important here. Maidan was in another country, citizens of another country were fighting for their freedom. The question is now for us whether we are ready to fight for our freedom, that’s all.”