The 68-year-old, famous for the "Wall of Sound" recording technique, faces between 15 years and life in prison.
He had pleaded not guilty to the second degree murder of 40-year-old Ms Clarkson, who was shot in the mouth at Spector's home in Los Angeles.
Spector remained quiet as the verdict was read out. He was remanded in custody until sentencing on 29 May.
