Linda Clarene Jackson was arrested at her home in Lake Los Angeles, where her boyfriend, David Ruiz, also 59, was pronounced dead at the scene, according to the Los Angeles County Sheriff's Department.
She was charged Thursday with one count of murder by using canned food as a "deadly and dangerous weapon," the District Attorney's Office said.
Jackson is being held in lieu of $1 million bail.
If convicted, she faces life in prison. There was no motive given for the attack.
Jackson has a 2005 conviction for making criminal threats.