A Maricopa County Superior Court spokeswoman said Anthony Rinaldi entered his plea of guilty Tuesday in the 2011 death of 28-year-old Amanda Blaies-Rinaldi.
Judge Rosa Mroz set sentencing for Nov. 26.
Phoenix police arrested Rinaldi after his wife's body was discovered in their Ahwatukee home.
Firefighters had responded to a call from a child that someone had been shot.
When responders arrived at the house, they discovered the body and two children inside the home.
The children were not harmed.