The verdict means Stewart is spared the death penalty.
Stewart had admitted to shooting 11 people, killing eight of them, at the Pinelake Health and Rehabilitation Center in Carthage. But In trying to spare his life, Stewart's defense lawyers said the 47-year-old was essentially sleepwalking at the time due to taking a combination of prescription drugs.
Prosecutors spent 13 days presenting witness testimony and physical evidence to make a case for a first-degree murder conviction.
Assistant District Attorney Tiffany Bartholomew said Stewart knew what he was doing and was on a rampage looking for his estranged wife, who worked at the nursing home.
She said the shooting started in the parking lot when Stewart shot up his wife's car and he paraded through the nursing home, reloading every three shots as he fired at the elderly patients at point-blank range.
Residents Tessie Garner, 75; Lillian Dunn, 89; Jesse Musser, 88; Bessie Hedrick, 78; John Goldston, 78; Margaret Johnson, 89; Louise DeKler, 98; and nurse Jerry Avant, 39 - all died in the gunfire.
Defense attorney Jon Megerian said Ambien and other drugs in Stewart's system caused him to be in a zombie-like state of mind when he entered the nursing home.
Megerian said Stewart was depressed because his wife, Wanda Neal, had recently left him and he thought he was going to die from prostate cancer.
Jurors deliberated for two days. While they also found Stewart guilty of other assorted assault charges, they found him not guilty of attempted first-degree murder for shooting Carthage police officer Justin Garner.
Garner stopped Stewart's rampage by shooting him in the chest. Garner was wounded in the leg by a blast from Stewart's shotgun.
The trial moved into the sentencing phase Saturday afternoon. Moore County Superior Court Judge James Webb heard from family members of the victims.
"That man killed my mom like she was a roach," said Linda Feola, whose mother, 98-year-old Louise DeKler, died in the attack.
In pleading Stewart's case, his defense said he was full of remorse, but couldn't remember anything.
Judge Webb sentenced Stewart to 189-236 months on each murder count for a total of 126-157 years in prison - essentially life in prison without possibility of parole.
Stewart also received another 16-22 years on the other charges.
The defense gave notice it intends to appeal.