Johnson had publicly denied for more than a year that he had kissed or groomed the fan, jurors at Bradford crown court were told.
He changed his plea to guilty on the first day of his trial on 10 February, prompting the club to terminate his contract 24 hours later.
Bradford Crown Court heard Johnson - who denies two further counts of sexual activity with a child - told the club he had kissed and exchanged messages with the girl when he met Sunderland chief executive Margaret Byrne on 4 May 2015.
Mrs Byrne was also issued with a copy of his police interview transcript and that of his alleged victim, the jury was told.
Giving evidence for the third day, Johnson said there had been no mention of him being sacked at the meeting or the potential consequences of admitting the charges.
His barrister Orlando Pownall QC asked him: "Was there any discussion of being summarily dismissed by the club? Was there any such discussion in the days that followed?"
Johnson replied to each question: "No."
The 28-year-old said he was not present at any decision made by the club with regard to his future, and he added his father received a phone call telling him his contract was being ended.
Referring to the players who were due to give evidence on Johnson's behalf, Mr Pownall asked: "Since you pleaded guilty, how has their approach been to you?"
Johnson said: "They took a step back."
In cross-examination, prosecutor Kate Blackwell QC said Johnson - who was earning $115,000 a week - had thrown away his career as a result of his "excessive arrogance".
Johnson replied: "I would say more stupidity."
The jury of eight women and four men has heard that Johnson met the girl twice in his black Range Rover after exchanging telephone numbers and messaging each other over a number of weeks.
Johnson denies that more serious sexual conduct took place between the pair in his car.
A friend of the girl told the court the alleged victim had been "bragging" about what had happened between her and the footballer.
The witness said she had told the girl she thought it had been wrong, but "she didn't care because he was a footballer".
She added: "She said that she was going to keep talking to him and she used to tell us how much money he made. She said she didn't care about his girlfriend and she was still going to do it."
Another friend, who the court heard had not wanted to give evidence, appeared via video link and said Johnson had been her friend's favourite player.
She said the girl had told her Johnson had performed a sex act on her and likewise, she on him.
She told the court: "I think she was a bit confused, she didn't know whether to be happy about it or worry."
The trial was adjourned until Thursday.