The girl, who has not been named for legal reasons, is being treated at a clinic after she wet herself during a 10-hour binge and even punched her dad in the face when he tried to confiscate the shoot-em-up game. "We got called in by her head teacher asking if everything was OK. Download it, boot up Fortnite on your PS4, and the skin will be in your inventory".
In a bid to wean her off Fortnite, the couple limited their daughter's game play to one hour on weekdays and two hours on weekends, but she refused to follow the rules.
After the parents discovered the girl sitting on the urine-soaked cushion, they asked her to tell the truth.
Once a keen sportswoman, the youngster starting saying she was too exhausted to do gym or ballet classes and avoided going to church on Sunday with her family.
She tearfully confessed she had been getting up in the middle of the night while they were asleep, sometimes playing the game until 5am.
The game has been endorsed by a large number of celebs who regularly upload videos of them playing the game.
Addictions counsellor Steve Pope, who treated the nine-year-old, said he had been contacted by parents of children as young as eight about possible Fortnite addictions.
Culture Secretary Matt Hancock has warned that addictive online shooter games can have a damaging impact on children. It's a complex, silly, and - most importantly - free game that's available on almost every platform: PC, Mac, iPhone/iPad, Xbox One, and PlayStation 4.
She is also said to have wet herself rather than pause the game.
She added: "This is a serious issue which is destroying our little girl's life and someone needs to step in to ban it before it becomes an epidemic".