The former Sunderland and Manchester City winger was sentenced to six years for engaging in sexual activity with a besotted 15-year-old fan in 2016.
Witnesses said Johnson’s father, Dave Johnson, was seen driving a Mercedes people carrier with blacked-out rear windows out of HMP Moorland, near Doncaster, South Yorkshire, in the early hours of Friday morning.
The vehicle was followed out the prison complex by a police van.
The same car was later spotted arriving at Johnson’s mansion in Castle Eden, County Durham.
Friday’s release comes exactly halfway through the player’s six-year sentence.
Johnson admitted kissing the girl but denied her claim that he touched her inside her pants and that she then performed oral sex on him.
A jury found him guilty of sexual activity with a child in relation to “digital penetration” but cleared him of the same offence relating to the oral sex.
He had already admitted another charge of sexual activity with a child in relation to kissing and also of grooming the girl.
The judge said Johnson had lied repeatedly, referring to the controversy over whether he delayed his guilty pleas to enable him to continue his £60,000-a-week career with Sunderland.
As a sex offender, Johnson will have to register his address and bank details with police and inform officers of any intention to travel abroad.
The children’s services department from the local council may also carry out risk assessments in relation to Johnson’s daughter Ayla, and could prevent Johnson from spending time alone with his daughter.