Bob Bashara of Grosse Pointe Park entered the plea Tuesday during a brief court appearance, The Detroit News reported Wednesday.
A conference to arrange a trial schedule was set for Aug. 17.
Joseph Gentz, who worked for Bashara as a handyman, has admitted killing Jane Bashara in January and says he acted at her husband's direction. Jane Bashara's body was discovered in an alley in Detroit inside her Mercedes SUV.
Mark Kriger, who became Bashara's lawyer last week, refused to talk to reporters and camera crews massed outside the courthouse.
"I don't talk about cases," he said.