If his death sentence doesn't hold up under appeal, he also faces a 185-year sentence from Circuit Judge John A. Gregory for seven other crimes he admitted committing related to his wife's fatal shooting.
A jury of seven women and five men agreed the 41-year-old father of two should die from a lethal injection. Gregory set Nov. 26, 2012, for the execution, but because appeals begin immediately in a capital case, it likely will take years to play out.
"Kim got her justice," said Kim Kirk Cox's mother, Melody Kirk of Myrtle, after the verdict slightly more than an hour after a Union County jury began deliberations.
Last August, Cox pleaded guilty to capital murder, kidnappings, multiple sexual assaults on a minor and other charges related to the May 14, 2010, standoff with law enforcement after Cox shot his wife twice and held captive two minors, including his own son. Kim Cox died about five hours later.
His sentence trial began Monday in the Union County Courthouse. A jury was seated late Tuesday and testimony began Wednesday.
The only sentence options were life without parole or death.
District Attorney Ben Creekmore said he was satisfied with the verdict.
"The jury made the appropriate sentence," he said Saturday. "I'm relieved."
T.R. Trout of New Albany, one of Cox's attorneys, said he'll begin the appeals process right away.
When the verdict was announced, Cox stood ramrod straight with little hint of emotions. Soon after, he was taken to the state penitentiary at Parchman. He's been held in the Union County Jail since his arrest in 2010 and escaped briefly a few months ago.
In phone conversations the night Kim Cox was shot, David Cox told various relatives he had intended to kill all the Kirks but impulsively decided to kill his wife a day early. He also said he didn't expect to come out of the trailer alive.
Melody Kirk said Cox's departure will "bring some peace" to the children now living with her. "They've been terrified he would break out again and get them," she said. "They sleep by our bed every night. It's been awful."
She and her husband, Bennie, expressed appreciation to the District Attorney's Office and law enforcement for their physical and emotional support since their daughter died.
Cox's attorneys tried to present testimony to engender mercy with the jury. Their witnesses told of Cox's poor, fatherless upbringing and of bullying he experienced at school. He dropped out in the sixth grade, ultimately to work as a long-haul truck driver.
They also pointed to a possible bipolar disorder and meth addiction.
Friday, a state forensic psychiatrist said a bipolar disorder diagnosis was wrong, although he did not dismiss its possibility.
The trial's most dramatic moment was perhaps its briefest - on Thursday when a 14-year-old girl wept as she confirmed an earlier recorded interview with her that Cox sexually assaulted her three times in front of his wife, so she would see it as she died.
"I don't think (author) John Grisham could write" a novel about "a more heinous crime" than Cox committed, Assistant District Attorney Kelly Luther told the jury Saturday morning.
Several dozen of Kim Cox's family and friends attended each day of the proceedings.
As the crowd left the courtroom, one of Cox's sisters hugged Melody Kirk, and said weeping, "I am so sorry."
Kirk said his family are victims, too.
The trial's length had unintended consequences for an annual Union County festival which had to be moved down the street from its usual site on the courthouse grounds.