It said on Monday the 42-year-old Gulf war veteran should face the electric chair or lethal injection for terrorism and capital murder.
Muhammad stood impassively in front of the jury as the ruling was read out, his hands clasped in front of him. He later shook hands with his attorney, Jonathan Shapiro, before being led away.
The judge tentatively set formal sentencing for 12 February to allow time for any post-trial motions.
The jury's findings came as prosecutors in the trial of his suspected accomplice, Lee Malvo, were set to wrap up their case.
Muhammad and Malvo each were charged with one murder in the series of 10 seemingly random sniper-style killings that spread fear in the Washington area in October 2002.
Muhammad was found guilty of two murder counts, conspiracy and a weapons charge on 17 November in the death of Dean Meyers, a Maryland man gunned down at a gas station on 9 October 2002, near Manassas, Virginia.
Attorneys for Malvo, who was 17 when the crimes were committed, plan to argue the teenager was brainwashed by Muhammad.
He is being tried as an adult in nearby Chesapeake, Virginia, and also faces a possible death sentence.
The trials were moved 320 km from the Washington area to southeastern Virginia in search of unbiased juries.
Members of both panels have indicated they were aware of the shootings, but said they could make up their minds based only on trial evidence.