The girl, who is now in intensive therapy to combat her addiction, would play for up to 10 hours a day.
It's the game that's taken over households. According to The Sun, Fornite has 40 million downloads since its launch, last July.
She is also said to have wet herself rather than pause the game.
Fortnite has exploded in popularity since launching in July past year. And as you can see in the image, it looks pretty close to what the actual in-game battle bus looks like with its blue colour scheme and balloon. A player's aim is to collect items while remaining in the safe zone, away from the storm which gets bigger, and to be the sole person left standing.
When they confronted their daughter about it, she said she had paid for extras on the Fortnite game.
Schools are writing to parents telling them the hugely popular game is having a disastrous affect on youngsters' concentration levels in the classroom.
A nine-year-old girl is in rehab after becoming so addicted to a video game she wet herself to avoid moving and hit her father when he tried to stop her playing.
And headteacher Jemma Garside, who runs a primary school in Stoke-on-Trent, Staffordshire, wrote to parents: 'Unfortunately discussions around this game are being brought ... into the classroom which is distracting children from their learning'.
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.
Carol said her "backside was red-raw, she was so hooked to the game she wouldn't even go to the toilet".
The girl is now recovering with rehabilitation.
Child psychologists believe kids could develop mental health problems if they become too exposed to the game.