Army psychiatrist Major Nidal Hasan, who shot dead 13 comrades at a Texas Army base in 2009, has been convicted of all charges.
Nidal Hasan, 42, faces the death penalty after being found guilty of 13 counts of pre-meditated murder and 32 counts of attempted murder.
He said he opened fire on the unarmed US soldiers to protect Taliban insurgents in Afghanistan.
The jury, which reached a unanimous verdict in seven hours, begins the penalty phase of the trial on Monday.
The 13-member panel must come to a unanimous agreement in order to recommend the judge sentence Major Nidal Hasan to death. If they do not agree, he will face a life prison sentence.
The US military has not executed a service member since 1961. There are five inmates on the US military’s death row at Fort Leavenworth, Kansas, all at various stages of the appeals process.
Among the last barriers to military execution is authorization from the president.
Nidal Hasan, a US-born Muslim of Palestinian descent, had no visible reaction as the verdict was read.
He admitted to being the gunman at the start of his court martial this month. Acting as his own lawyer, he questioned only three of 90 prosecution witnesses and declined to call witnesses of his own or make closing arguments.
His court-appointed legal advisers, who were little involved in his defense, have told the judge they believed he sought execution.
Nidal Hasan has said he carried out the attack on unarmed soldiers at a medical building at Fort Hood in order to protect Taliban fighters in Afghanistan, but the judge, Colonel Tara Osborn, barred him from presenting that argument in court.
The Army psychiatrist opened fire on 5 November 2009 at a medical facility on the base where soldiers were being evaluated before deploying overseas.
Prosecutors said he had prepared carefully for the attack for weeks, visiting a target practice range, buying a gun, and stuffing paper towels into his trouser pockets to muffle noise from the extra ammunition before he opened fire.
Soldiers and civilians testified they heard a man scream an Islamic benediction, then saw a man in Army camouflage open fire with two handguns.
Witnesses also said Nidal Hasan’s rapid reloading prevented the unarmed soldiers from halting the attack. Three separate people who attempted to charge him were stopped by gunfire.
Nidal Hasan fired 146 bullets, prosecutors said. The attack ended when he was shot by a civilian police officer. He was paralyzed from the waist down from the wound.