Ms Politkovskaya, an investigative reporter who uncovered state corruption and rights abuses, was gunned down in the lobby of her Moscow apartment block at the age of 48 on October 7, 2006, President Vladimir Putin's 54th birthday.
The Russian authorities denied any role in the killing, which caused international outrage.
The five men, convicted by a jury last month, exchanged nervous smiles in their glass-fronted courtroom cage before judge Pavel Melyokhin handed down the sentences.
He agreed to the prosecutors' request to order life imprisonment for Rustam Makhmudov, found guilty of pulling the trigger, and his uncle Lom-Ali Gaitukayev, who organised the logistics. The other three received 12, 14 and 20 years.
Ms Politkovskaya was one of nearly two dozen journalists murdered in Russia since 2000, but her case attracted special attention because of the brutality of the contract-style killing and the failure of the authorities even now, after nearly eight years and several trials, to identify who ordered the assassination.
Kremlin critics and rights campaigners say the murder symbolises the weakness of the rule of law in Russia.