Sixteen others were jailed for between 10 and 20 years at a hearing in Tashkent, the capital of the Central Asian republic, in which observers said defendants were denied access to their chosen lawyers and were convicted on the basis of confessions, without any scientific evidence.
The Uzbek security services have been criticised in the past by human rights groups and others for using torture to obtain confessions.
The accused were arrested by the security services after six large bombs exploded in the centre of Tashkent in February, killing 16 people and injuring 120. President Karimov, a former Communist Party boss known as "Papa", declared the bombings to be an attempt on his life by Islamic militants.
News reports said he was in the area when the explosions happened.
"There were glaring irregularities in the trial," said Acacia Shields, of Human Rights Watch, who monitored each day of the hearings. "These included an absence of the presumption of innocence and denial of the right to legal counsel of their choice. The authorities neglected to present evidence to prove that the defendants were guilty. No material evidence was presented whatsoever." She described the proceedings as a "show trial".
The trial is also understood to have caused considerable concern, for similar reasons, within the Organisation for Security and Co-Operation in Europe, which is compiling an internal report on the issue.
As is common in the former Soviet Union, the defendants spent the entire trial inside an iron cage in the courtroom. After they were convicted, they were followed on their journey to prison by a convoy of wailing relatives. They have 10 days to appeal to the presidium of the Supreme Court, appointed by Mr Karimov.
In the aftermath of the February bombings, the government - long fearful of Muslim fundamentalism spilling over from Tajikistan, Afghanistan and Chechnya - sharply increased its efforts to crush Islamic opposition groups.
Human Rights Watch claims that the net went wider to include thousands of Uzbeks who were "terrorised" by the authorities. These includedMikhail Ardzinov, a leading local human rights activist who was badly beaten by the police last week.
They arrested him en route to the trial and held him for more than 13 hours. An examination by a doctor at the US embassy found that he had two broken ribs, concussion and damaged kidneys.Reuse content