The Army psychiatrist acknowledged carrying out the attack in a crowded waiting room where unarmed troops were making final preparations to deploy to Afghanistan and Iraq.
A jury of 13 high-ranking military officers reached a unanimous guilty verdict on all charges, which included 13 counts of premeditated murder and 32 counts of attempted premeditated murder. Hasan is now eligible for the death penalty.
Hasan acted as his own attorney but declined to plead his case after prosecutors finished their closing argument. When the judge told Hasan he could begin, he said: "The defense chooses not to make a closing statement."
The shooting rampage was the deadliest ever on a U.S. military base.
Prosecutors laid out a detailed roadmap of their case during their closing argument, saying there was no question that Hasan planned and carried out the attack. Hasan told jurors during a brief opening statement nearly two weeks ago that evidence would "clearly show" he was the shooter, and he described himself as a soldier who had "switched sides."
But since then, he has sat mostly silent in his wheelchair. Hasan, who was paralyzed after being shot by officers responding to the attack, has raised few objections during the 13-day trial. He questioned only three of the nearly 90 witnesses called by prosecutors, and the only piece of evidence he submitted was an evaluation from his boss that called him a good soldier.
The Associated Press contributed to this report.