Kovalyov and Konovalov will be executed with a bullet to the back of the head.
Konovalov, 25, a lathe operator, was found guilty of this year's metro blast, and several smaller attacks stretching back a decade.
Kovalyov, also 25, an electrician, was found guilty of aiding and abetting his childhood friend.
The prosecution failed to come up with a convincing motive for the terrorist acts.
The case relied almost entirely on confessions from the two men.
Konovalov refused to speak during the court hearing, while Kovalyov went back on his testimony. He said he had been told he would be let off lightly if he implicated his friend, and that he could hear Konovalov screaming from torture during the investigation, and did not want to suffer the same fate.
Without the confessions, much of the remaining evidence is circumstantial and full of holes, according to independent observers. Time after time yesterday, when the judge stated facts had been proved by the evidence, there were angry shouts from the hall. Later, people began cackling at points that struck them as absurd.
And then, it wasn't funny any more. The judge sentenced both of the pair to "the most exceptional punishment - death". The defendants did not register any change in expression, but in the gallery shouts of "Disgrace!" and "Butcher!" went up, aimed at the judge.
International organisations condemned the verdict. "Belarus has a flawed justice system and routinely flouts international fair trial standards, increasing the risk of a miscarriage of justice and of executing an innocent person," said John Dalhuisen of Amnesty International.
There have also been accusations that Lukashenko effectively ordered the court how to rule, by rewarding officials for solving the crime before the court had announced its verdict.
- INDEPENDENT