Tsarnaev, flanked by his lawyers, sat at a table at the front of the jury assembly room in Boston. Wearing a dark jumper and khaki trousers, he picked at his beard, looked at the potential jurors and looked at the judge.
Over the next three days, about 1,200 people will be called to federal court to be considered as potential jurors. Twelve jurors and six alternatives are to be selected.
The judge said the trial would begin on January 26 and last three to four months.
Prosecutors say Dzhokhar, 21, and his brother, Tamerlan Tsarnaev, ethnic Chechens who had lived in the US for about a decade, carried out the bombings as retaliation for US actions in Muslim countries. Tamerlan, 26, died after a firefight with police.