The final decision was made by Attorney General Eric Holder and was announced Thursday. The twin blasts in April killed three people and wounded more than 260 in one of the most prominent terrorist attacks in the U.S since 9/11.
Prosecutors allege that Tsarnaev and his brother, Tamerlan, ethnic Chechens from Russia who had lived in the Boston area for about a decade, planted two pressure cooker bombs near the finish line. Tamerlan Tsarnaev died in a shootout with police.
Seventeen of 30 charges against Tsarnaev carry the possibility of the death penalty, including using a weapon of mass destruction to kill.
The 20-year-old Tsarnaev has pleaded not guilty. No trial date has been set.