The 27-year-old England international, who appeared in the dock at Durham Crown Court dressed in a grey suit and white shirt, also denied one charge of grooming.
Johnson entered the court surrounded by his legal team, and spoke to enter his not guilty pleas.
The winger was arrested in March after he was accused of sexual activity with a 15-year-old girl.
The three counts of sexual activity with a child were alleged to have taken place on one night in January at two locations in County Durham, while the offence of meeting a child after sexual grooming was alleged to have happened between December and February.
It was agreed in court that the trial would go ahead at Durham and Judge Christopher Prince set a date of August 24.
The winger, who has played 12 times for England, lives in Castle Eden, County Durham.
Born in Sunderland, Johnson began his career at Middlesbrough before moving to Manchester City and then Sunderland for £10million in 2012.