Johnson had earlier denied all four of the allegations until the first day of his trial when he pleaded guilty to one count of grooming and one count of kissing the schoolgirl.
Judge Jonathan Rose, upon pronouncing judgement told Johnson: “All of this is entirely your own responsibility and fault."
The judge said the victim had been a Sunderland fan who would wait after matches to take pictures of her “favourite player”, Johnson, who had known her age.
“That was known to you - to put it another way she had only just turned 15 when you began grooming her, because as you were to admit you found her sexually attractive. You continued in your grooming of this girl even after you were engaged in sexual activity with her. You wanted no-one to know that you and she were exchanging messages. You asked her to find a place to meet that was private and secluded so no-one would see you in her company. You made a deliberate decision to engage in sexual activity with this young girl, no doubt in the expectation that you would get away with it. Your future as a professional footballer must be in doubt.”