Sherry Halligan showed no visible reaction as Judge Hohn Hynes gave his verdict after a 5-day bench trial in Bridgeview Branch Court.
The family of victim Dennis Campbell hugged after the verdict.
Earlier this week, Halligan told Hynes she shot Campbell after an explosive fight that began when she refused to sleep with his boss.
Halligan, a real estate appraiser who now is 54, took the stand 10 years to the day since she emptied her revolver into Campbell in her La Grange home, shut a door so she didn't hear his dying moans and drove all night on Interstate 55, tossing the gun out a window before reversing course and turning herself in to police, according to testimony.
After she was charged with murder and posted bond, Halligan eluded authorities and her case was featured on "America's Most Wanted." She left her car near Midway Airport in 2004, sold some jewelry, lived under her grandmother's name and moved in with a new man.
Halligan was confident enough in 2005 to get an Illinois driver's license, and she testified that she dyed her hair red in her last two years on the run only after she no longer could dye her graying hair blond.
It all ended in 2010, when an FBI agent and two La Grange cops knocked on the door of her Palos Hills condo. The woman living as Katherine White quickly admitted she was Halligan, officers testified.
Earlier in the trial, she spoke in her own defense, claiming Campbell was abusive and that years of being beaten and sexually assaulted by boyfriends left her suffering from battered woman syndrome. She said one boyfriend also forced her to work for an escort service when she was younger.
Prosecutors, meanwhile, contended that Halligan carefully planned the murder when
Sentencing for Halligan is set for Feb. 27.