The man accused of bombing the Boston Marathon in 2013 has been found guilty of all 30 charges that he faced, many of which carry the death penalty.
The jury in Massachusetts will now decide what sentence 21-year-old Dzhokhar Tsarnaev will receive.
Three people - Martin Richard, eight, Lu Lingzi and Krystle Campbell - were killed and more than 260 injured when the bombs exploded at the finish line in April 2013.
His lawyers maintained he played a role in the attacks but said his older brother was the driving force.
A police officer was killed in the days following the attack as Tsarnaev and his brother, who also died, attempted to flee.
The decision was reached on Wednesday, after the jury deliberated for just over 12 hours over two days.
Tsarnaev kept his hands folded in front of him and looked down as the guilty verdicts were read.
Nearby, Martin Richard's mother wiped tears from her face after the verdict was read. Richard's father embraced one of the prosecutors.
Karen Brassard, who was injured along with her husband and daughter, said she needed to witness the trial to help her process the trauma.
She said Tsarnaev showed no emotion when convicted.
"Personally I wouldn't have bought it. I would have been more frustrated if he had shown it, because throughout this whole thing he's been, to use my word, arrogant, walking in and out of the courtroom and completely disinterested.
"So if I saw anything from him today, I would have been a little more frustrated."
The governor of Massachusetts welcomed the verdict, and Boston Mayor Martin Walsh said: "I hope today's verdict provides a small amount of closure."
The conviction was widely expected because Tsarnaev's chief lawyer, Judy Clarke, made the surprise admission during opening statements that he took part in the bombing.
That admission was part of a defence strategy to paint Tsarnaev's elder brother, Tamerlan, as the mastermind of the attack who influenced Tsarnaev into participating.
Prosecutors portrayed them as equal partners in a plan to "punish America" for wars in Muslim countries.
Among the most damning evidence was a video that showed Tsarnaev placing a backpack bomb near Martin Richard, and a statement scrawled inside the boat where he was found hiding days after the attack.
"Stop killing our innocent people and we will stop," he wrote, as he lay wounded and bleeding inside the dry-docked boat in suburban garden.
The jury was also shown a surveillance video of Tsarnaev casually buying milk at a nearby supermarket less than 30 minutes after the bombs wreaked carnage at the finish line.
The jury will now have to decide whether Tsarnaev faces the death penalty as the trial moves into its second phase, which could begin as early as Monday.
Tsarnaev is an ethnic Chechen. His family moved to the United States about a decade before the bombings.