Kevin Liverpool, 34, of Manchester pleaded not guilty to charges he conspired to rob and kill Stone.
Junior Bradshaw, 31, also charged in the alleged plot, appeared in court but did not enter a plea, the BBC reported. The two men, who were arrested in June in Cullompton, Devon, near the singer's home, were remanded.
The case was adjourned until December with trial scheduled for August.
Stone, 24, did not appear in court but the BBC said her mother Wendy was in the public gallery.
Celebrity Breakups and divorces of 2014 [PHOTOS]