The 28-year-old faces two other charges of sexual activity with a child aged under 16 years.
The Sunderland winger's trial is being heard at Bradford Crown Court.
Johnson's partner Stacey Flounders - mother to their one-year-old girl - was present in court, sat alongside Johnson's father.
Johnson had initially denied all four charges against him, but today he changed his plea to guilty on two of the counts.
The jury which was sworn in today was told that Johnson has pleaded guilty to two charges.
Jurors heard that the case will open on Friday, and Judge Jonathan Rose warned them that they can only consider evidence which is presented in court.
'You may see reference to this in the press but it's the evidence in court that you will gather,' he said.
'This defendant has already pleaded guilty to two offences, you will hear more about them in detail when Miss Blackwell opens the case to you on Friday.'
Miss Flounders, 26, has stood by Johnson since the claims first emerged. The couple had a baby together just a few weeks before his initial arrest.
The sexual offences are alleged to have taken place at two locations in County Durham on a night in January 2015.
Johnson began his career at Middlesbrough before moving to Manchester City and then transferred to Sunderland for £10million in 2012.
He has represented England 12 times between 2010 and 2012, scoring two goals.
The player was initially suspended by Sunderland in the wake of his arrest, but he was then allowed to return to the team.