Uzbekistan's supreme court found all 15 men guilty of murder, rioting, hostage-taking, membership of banned Islamist groups and attempting to establish an Islamist caliphate in the town of Andijan, where up to 700 people were killed by security forces in May.
The men, who pleaded guilty during a five-hour session in which they were confined in a metal cage, face from 14 to 20 years in prison.
Human rights groups have dismissed the government's version of events, and the evidence of a state-orchestrated massacre has shamed previous allies of President Islam Karimov in Washington and London into demanding action from Uzbekistan. But Mr Karimov has been received with open arms in Moscow, where he and President Vladimir Putin signed a military pact yesterday pledging mutual help in fighting security threats.
Campaigners say the 15 men are scapegoats for a civilian massacre, that they were tortured into confessing, and that their trial resembled Stalin's show trials of the 1930s.
The attempted "coup" was brutally put down by Uzbek security forces whom human rights groups accuse of turning their fire on civilians and of mowing down between 500 and 700 people, most of them unarmed.
Mr Karimov's hardline regime, which became a pariah state overnight, insists that only 187 people were killed and that most of the dead were " terrorists" who were planning to overthrow the government with the help of foreign extremists and radical Islamist groups such as Hizb ut-Tahrir, the Islamic Movement of Uzbekistan, and the Islamic Movement of Turkestan. It said it had no choice but to get tough.
The court in Tashkent, the Uzbek capital, sentenced five of the defendants to 20 years' jail, one to 18 years, three to 17 years, two to 16 and the other four to 14 years. The judge said the men had planned to blow up a mountain pass sealing off the volatile Ferghana valley, where Andijan is located. He repeated government allegations that foreign media had exaggerated the event and acted irresponsibly by portraying the "coup" as a peaceful demonstration.
The trial has been condemned by the United Nations Commission on Human Rights, which has pointed to serious procedural problems, such as the fact that the 15 men were not cross-examined by independent lawyers.
America's discomfort with the massacre saw relations between Tashkent and Washington deteriorate and led to Mr Karimov asking the US military to shut down an air base in the south-east of the country.
Earlier this year the European Union imposed "smart sanctions" on Tashkent after Uzbekistan rejected calls for an international inquiry into Andijan.
At the same time, Mr Karimov's relations with Russia have improved. Yesterday Mr Karimov was welcomed at the Kremlin by Mr Putin where they signed a strategic military alliance which gives Russia back some of the influence it lost in Uzbekistan when the Soviet Union collapsed in 1991. Under the terms of the pact the two countries have the right to offer assistance to one another and use each other's military facilities in the event of a crisis or third party aggression.